Interleukins (ILs) are a group of cytokines (secreted proteins and signal molecules ) that are expressed and secreted by white blood cells (leukocytes) as well as some other body cells. The human genome encodes more than 50 interleukins and related proteins.
129-488: The function of the immune system primarily depends on interleukins, and rare deficiencies of a number of them have been described, all featuring autoimmune diseases or immune deficiency . The majority of interleukins are synthesized by CD4 helper T-lymphocytes , as well as through monocytes , macrophages , and endothelial cells. They promote the development and differentiation of T and B lymphocytes , and hematopoietic cells. Interleukin receptors on astrocytes in
258-564: A lysosome to form a phagolysosome . The pathogen is killed by the activity of digestive enzymes or following a respiratory burst that releases free radicals into the phagolysosome. Phagocytosis evolved as a means of acquiring nutrients , but this role was extended in phagocytes to include engulfment of pathogens as a defense mechanism. Phagocytosis probably represents the oldest form of host defense, as phagocytes have been identified in both vertebrate and invertebrate animals. Neutrophils and macrophages are phagocytes that travel throughout
387-465: A "self" receptor called a major histocompatibility complex (MHC) molecule. There are two major subtypes of T cells: the killer T cell and the helper T cell . In addition there are regulatory T cells which have a role in modulating immune response. Killer T cells are a sub-group of T cells that kill cells that are infected with viruses (and other pathogens), or are otherwise damaged or dysfunctional. As with B cells, each type of T cell recognizes
516-435: A T Cell Receptor (a TCR) and an HLA-peptide complex. As a result of that conjunction a signalling pathway (signalling a cell's protein making machinery to express or 'make' IL-2), a PhosphoLipase-C (PLC) dependent pathway, is set up. PLC activates 3 major transcription factors and their pathways: NFAT , NFkB and AP-1 . In addition and after costimulation from CD28 the optimal activation of expression of IL-2 and these pathways
645-407: A broad range of doses, without serious side effects. Tumour blood vessels are more vulnerable than normal blood vessels to the actions of IL-2. When injected inside a tumor, i.e. local application, a process mechanistically similar to the vascular leakage syndrome, occurs in tumor tissue only. Disruption of the blood flow inside of the tumor effectively destroys tumor tissue. In local application,
774-423: A chemical barrier following menarche , when they become slightly acidic , while semen contains defensins and zinc to kill pathogens. In the stomach , gastric acid serves as a chemical defense against ingested pathogens. Within the genitourinary and gastrointestinal tracts, commensal flora serve as biological barriers by competing with pathogenic bacteria for food and space and, in some cases, changing
903-417: A compact, globular fold (similar to other interleukins), stabilised by the two disulphide bonds. One half of the structure is dominated by a 4-alpha-helix bundle with a left-handed twist; the helices are anti-parallel, with two overhand connections, which fall into a double-stranded anti-parallel beta-sheet. The fourth alpha-helix is important to the biological activity of the molecule. Interleukin 7 (IL-7)
1032-422: A condition known as "missing self". This term describes cells with low levels of a cell-surface marker called MHC I ( major histocompatibility complex )—a situation that can arise in viral infections of host cells. Normal body cells are not recognized and attacked by NK cells because they express intact self MHC antigens. Those MHC antigens are recognized by killer cell immunoglobulin receptors, which essentially put
1161-584: A different antigen. Killer T cells are activated when their T-cell receptor binds to this specific antigen in a complex with the MHC Class I receptor of another cell. Recognition of this MHC:antigen complex is aided by a co-receptor on the T cell, called CD8 . The T cell then travels throughout the body in search of cells where the MHC I receptors bear this antigen. When an activated T cell contacts such cells, it releases cytotoxins , such as perforin , which form pores in
1290-533: A diminished effect and may result in lower antibody production, and a lower immune response, than would be noted in a well-rested individual. Additionally, proteins such as NFIL3 , which have been shown to be closely intertwined with both T-cell differentiation and circadian rhythms , can be affected through the disturbance of natural light and dark cycles through instances of sleep deprivation. These disruptions can lead to an increase in chronic conditions such as heart disease, chronic pain, and asthma. In addition to
1419-549: A free cytokine, mammalian IL-2 that is secreted by activated T cells is important for a negative feedback loop by the stimulation of regulatory T cells, the latter being the cells with the highest constitutive IL-2Rα (aka CD25) expression. Besides this negative feedback loop, mammalian IL-2 also participates in a positive feedback loop because activated T cells enhance their own IL-2Rα expression. As in mammals, fish IL-2 also stimulates T cell proliferation and appears to preferentially stimulate regulatory T cells. Fish IL-2 induces
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#17328869040411548-585: A growth factor and antibody production stimulant. The protein is secreted as a single glycosylated polypeptide, and cleavage of a signal sequence is required for its activity. Solution NMR suggests that the structure of IL2 comprises a bundle of 4 helices (termed A-D), flanked by 2 shorter helices and several poorly defined loops. Residues in helix A, and in the loop region between helices A and B, are important for receptor binding. Secondary structure analysis has suggested similarity to IL4 and granulocyte-macrophage colony stimulating factor (GMCSF). Interleukin 3 (IL3)
1677-491: A hyperactive immune system attacking normal tissues as if they were foreign organisms. Common autoimmune diseases include Hashimoto's thyroiditis , rheumatoid arthritis , diabetes mellitus type 1 , and systemic lupus erythematosus . Immunology covers the study of all aspects of the immune system. The immune system protects its host from infection with layered defenses of increasing specificity. Physical barriers prevent pathogens such as bacteria and viruses from entering
1806-500: A key role in inflammation of many autoimmune diseases, such as RA, allergies, asthma, psoriasis, and more, but it also plays a key role in the pathogenesis of these diseases. Additionally, some studies have found that IL-17 plays a role in tumorigenesis (initial formation of a tumor) and transplant rejection. The IL-17 family is thought to represent a distinct signaling system that appears to have been highly conserved across vertebrate evolution. Immune system The immune system
1935-399: A link between the bodily tissues and the innate and adaptive immune systems, as they present antigens to T cells , one of the key cell types of the adaptive immune system. Granulocytes are leukocytes that have granules in their cytoplasm. In this category are neutrophils, mast cells, basophils, and eosinophils. Mast cells reside in connective tissues and mucous membranes and regulate
2064-456: A manner reminiscent of how mammalian IL-15 binds to IL-15Rα. Despite fish IL-2 and IL-15 sharing the same IL-15Rα chain, the stability of fish IL-2 is independent of it whereas IL-15 and especially IL-15L depend on binding to (co-presentation with) IL-15Rα for their stability and function. This suggests that, like in mammals, fish IL-2, in contrast to fish IL-15 and IL-15L, is not relying on "in trans" presentation by its receptor alpha chain. As
2193-406: A point of disagreement. The commercial interest in local IL-2 therapy has been very low. Because only a very low dose IL-2 is used, treatment of a patient would cost about $ 500 commercial value of the patented IL-2. The commercial return on investment is too low to stimulate additional clinical studies for the registration of intratumoral IL-2 therapy. Usually, in the U.S., the higher dosage option
2322-635: A preconfigured response to broad groups of situations and stimuli. The adaptive immune system provides a tailored response to each stimulus by learning to recognize molecules it has previously encountered. Both use molecules and cells to perform their functions. Nearly all organisms have some kind of immune system. Bacteria have a rudimentary immune system in the form of enzymes that protect against viral infections. Other basic immune mechanisms evolved in ancient plants and animals and remain in their modern descendants. These mechanisms include phagocytosis , antimicrobial peptides called defensins , and
2451-460: A pro-inflammatory state through the production of the pro-inflammatory cytokines interleukin-1, interleukin-12 , TNF-alpha and IFN-gamma . These cytokines then stimulate immune functions such as immune cell activation, proliferation, and differentiation . During this time of a slowly evolving adaptive immune response, there is a peak in undifferentiated or less differentiated cells, like naïve and central memory T cells. In addition to these effects,
2580-400: A promising immunotherapeutic agent due to significant drawbacks which are listed above. Some of the issues can be overcome using IL-2 ic. They are composed of IL-2 and some of its monoclonal antibody (mAb) and can potentiate biologic activity of IL-2 in vivo . The main mechanism of this phenomenon in vivo is due to the prolongation of the cytokine half-life in circulation. Depending on
2709-511: A recent study has shown that IL-9 is, in fact, much closer to both IL-2 and IL-15, than to IL-7. Moreover, the study showed irreconcilable structural differences between IL-7 and all the remaining cytokines signalling through the γc receptor ( IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21). Interleukin 10 (IL-10) is a protein that inhibits the synthesis of a number of cytokines, including IFN-gamma, IL-2, IL-3, TNF, and GM-CSF produced by activated macrophages and by helper T cells. In structure, IL-10
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#17328869040412838-491: A reduced ability to destroy pathogens, is an example of an inherited, or congenital, immunodeficiency . AIDS and some types of cancer cause acquired immunodeficiency. Overactive immune responses form the other end of immune dysfunction, particularly the autoimmune diseases . Here, the immune system fails to properly distinguish between self and non-self, and attacks part of the body. Under normal circumstances, many T cells and antibodies react with "self" peptides. One of
2967-416: A similar genomic location. In fish, IL-2 shares a single receptor alpha chain with its related cytokines IL-15 and IL-15-like (IL-15L). This "IL-15Rα" receptor chain is similar to mammalian IL-15Rα, and in tetrapod evolution a duplication of its coding gene plus further diversification created mammalian IL-2Rα. Sequences, and structural analysis of grass carp IL-2, suggest that fish IL-2 binds IL-15Rα in
3096-471: A single MHC:antigen molecule. Helper T cell activation also requires longer duration of engagement with an antigen-presenting cell. The activation of a resting helper T cell causes it to release cytokines that influence the activity of many cell types. Cytokine signals produced by helper T cells enhance the microbicidal function of macrophages and the activity of killer T cells. In addition, helper T cell activation causes an upregulation of molecules expressed on
3225-460: A specific foreign antigen. This antigen/antibody complex is taken up by the B cell and processed by proteolysis into peptides . The B cell then displays these antigenic peptides on its surface MHC class II molecules. This combination of MHC and antigen attracts a matching helper T cell, which releases lymphokines and activates the B cell. As the activated B cell then begins to divide , its offspring ( plasma cells ) secrete millions of copies of
3354-737: A wide variety of body cells. The term was coined by Dr Vern Paetkau, University of Victoria . Some interleukins are classified as lymphokines , lymphocyte-produced cytokines that mediate immune responses. Interleukin 1 alpha and interleukin 1 beta ( IL1 alpha and IL1 beta ) are cytokines that participate in the regulation of immune responses, inflammatory reactions, and hematopoiesis. Two types of IL-1 receptor, each with three extracellular immunoglobulin (Ig)-like domains, limited sequence similarity (28%) and different pharmacological characteristics have been cloned from mouse and human cell lines: these have been termed type I and type II receptors. The receptors both exist in transmembrane (TM) and soluble forms:
3483-465: Is a cytokine that regulates hematopoiesis by controlling the production, differentiation and function of granulocytes and macrophages. The protein, which exists in vivo as a monomer, is produced in activated T cells and mast cells, and is activated by the cleavage of an N-terminal signal sequence. IL3 is produced by T lymphocytes and T-cell lymphomas only after stimulation with antigens, mitogens, or chemical activators such as phorbol esters. However, IL3
3612-455: Is a cytokine that serves as a growth factor for early lymphoid cells of both B- and T-cell lineages. Interleukin 8 is a chemokine produced by macrophages and other cell types such as epithelial cells , airway smooth muscle cells and endothelial cells. Endothelial cells store IL-8 in their storage vesicles, the Weibel-Palade bodies . In humans, the interleukin-8 protein is encoded by
3741-414: Is a homodimer. The fold contains an anti-parallel 4-alpha-helix bundle with a left handed twist, connected by a 2-stranded anti-parallel beta-sheet. The monomers are held together by 2 interchain disulphide bonds. Interleukin 6 (IL6), also referred to as B-cell stimulatory factor-2 (BSF-2) and interferon beta-2, is a cytokine involved in a wide variety of biological functions. It plays an essential role in
3870-417: Is a network of biological systems that protects an organism from diseases . It detects and responds to a wide variety of pathogens , from viruses to bacteria , as well as cancer cells , parasitic worms , and also objects such as wood splinters , distinguishing them from the organism's own healthy tissue . Many species have two major subsystems of the immune system. The innate immune system provides
3999-573: Is a protein of about 160 amino acids that contains four conserved cysteines involved in disulphide bonds. IL-10 is highly similar to the Human herpesvirus 4 (Epstein-Barr virus) BCRF1 protein, which inhibits the synthesis of gamma-interferon and to Equid herpesvirus 2 (Equine herpesvirus 2) protein E7. It is also similar, but to a lesser degree, with human protein mda-7. a protein that has antiproliferative properties in human melanoma cells. Mda-7 contains only two of
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4128-457: Is a recombinant IL-2 with a serine at residue 125, sold by Shenzhen Neptunus. Neoleukin 2/15 is a computationally designed mimic of IL-2 that was designed to avoid common side effects. However, clinical trials into this candidate were discontinued. Various dosages of IL-2 across the United States and across the world are used. The efficacy and side effects of different dosages is often
4257-409: Is a transient immunodepression, where the number of circulating lymphocytes decreases and antibody production declines. This may give rise to a window of opportunity for infection and reactivation of latent virus infections, but the evidence is inconclusive. During exercise there is an increase in circulating white blood cells of all types. This is caused by the frictional force of blood flowing on
4386-446: Is activated by complement binding to antibodies that have attached to these microbes or the binding of complement proteins to carbohydrates on the surfaces of microbes . This recognition signal triggers a rapid killing response. The speed of the response is a result of signal amplification that occurs after sequential proteolytic activation of complement molecules, which are also proteases. After complement proteins initially bind to
4515-527: Is affected by sleep and rest, and sleep deprivation is detrimental to immune function. Complex feedback loops involving cytokines , such as interleukin-1 and tumor necrosis factor-α produced in response to infection, appear to also play a role in the regulation of non-rapid eye movement ( REM ) sleep. Thus the immune response to infection may result in changes to the sleep cycle, including an increase in slow-wave sleep relative to REM sleep. In people with sleep deprivation, active immunizations may have
4644-502: Is also recognized by the helper cell's CD4 co-receptor, which recruits molecules inside the T cell (such as Lck ) that are responsible for the T cell's activation. Helper T cells have a weaker association with the MHC:antigen complex than observed for killer T cells, meaning many receptors (around 200–300) on the helper T cell must be bound by an MHC:antigen to activate the helper cell, while killer T cells can be activated by engagement of
4773-579: Is an interleukin , a type of cytokine signaling molecule in the immune system . It is a 15.5–16 kDa protein that regulates the activities of white blood cells (leukocytes, often lymphocytes ) that are responsible for immunity. IL-2 is part of the body's natural response to microbial infection , and in discriminating between foreign ("non-self") and "self". IL-2 mediates its effects by binding to IL-2 receptors , which are expressed by lymphocytes. The major sources of IL-2 are activated CD4 T cells and activated CD8 T cells . Put shortly
4902-549: Is an immune response that damages the body's own tissues. It is divided into four classes (Type I – IV) based on the mechanisms involved and the time course of the hypersensitive reaction. Type I hypersensitivity is an immediate or anaphylactic reaction, often associated with allergy. Symptoms can range from mild discomfort to death. Type I hypersensitivity is mediated by IgE , which triggers degranulation of mast cells and basophils when cross-linked by antigen. Type II hypersensitivity occurs when antibodies bind to antigens on
5031-415: Is an important feature of cellular innate immunity performed by cells called phagocytes that engulf pathogens or particles. Phagocytes generally patrol the body searching for pathogens, but can be called to specific locations by cytokines. Once a pathogen has been engulfed by a phagocyte, it becomes trapped in an intracellular vesicle called a phagosome , which subsequently fuses with another vesicle called
5160-477: Is commenced by IL-2 binding to its receptor, following which cytoplasmatic domains of CD122 and CD132 heterodimerize . This leads to the activation of Janus kinases JAK1 and JAK3 which subsequently phosphorylate T338 on CD122. This phosphorylation recruits STAT transcription factors , predominantly STAT5 , which dimerize and migrate to the cell nucleus where they bind to DNA . with an "express other proteins" signal. The proteins expressed by means of
5289-572: Is constitutively expressed in the myelomonocytic leukaemia cell line WEHI-3B. It is thought that the genetic change of the cell line to constitutive production of IL3 is the key event in development of this leukaemia. Interleukin 4 (IL4) is produced by CD4 T cells specialized in providing help to B cells to proliferate and to undergo class switch recombination and somatic hypermutation. Th2 cells, through production of IL-4, have an important function in B-cell responses that involve class switch recombination to
Interleukin - Misplaced Pages Continue
5418-539: Is dephosphorylated and therefore translocated to the nucleus. AP-1 is a dimer and is composed of c-Jun and c-Fos proteins. It cooperates with other transcription factors including NFkB and Oct. NFkB is translocated to the nucleus after costimulation through CD28. NFkB is a heterodimer and there are two binding sites on the IL-2 promoter. IL-2 has essential roles in key functions of the immune system, tolerance and immunity , primarily via its direct effects on T cells . In
5547-560: Is expressed by memory CD8 T cells and NK cells , whereas regulatory T cells and activated T cells express high levels of trimeric IL-2R. Instructions to express proteins in response to an IL-2 signal (called IL-2 transduction) can take place via 3 different signaling pathways ; they are: (1) the JAK-STAT pathway, (2) the PI3K/Akt/mTOR pathway and (3) the MAPK/ERK pathway. The signalling
5676-419: Is generally well tolerated. This is also the case for intralesional IL-2 in other forms of cancer, like nasopharyngeal carcinoma. Eisai markets a drug called denileukin diftitox (trade name Ontak), which is a recombinant fusion protein of the human IL-2 ligand and the diphtheria toxin . This drug binds to IL-2 receptors and introduces the diphtheria toxin into cells that express those receptors, killing
5805-557: Is generated by the proteolytic cleavage of an inactive precursor molecule. A complementary DNA encoding protease that carries out this cleavage has been cloned. Recombinant expression enables cells to process precursor Interleukin 1 Beta to the mature form of the enzyme. Interleukin 1 also plays a role in the central nervous system . Research indicates that mice with a genetic deletion of the type I IL-1 receptor display markedly impaired hippocampal-dependent memory functioning and long-term potentiation , although memories that do not depend on
5934-608: Is induced. In summary therefore before a cell will make IL-2 in accordance with this pathway there have to be two reactions: TCR+HLA and protein complex on the one hand and CD28 costimulation on the other indeed mere IL-2 ligation to its receptor is too low affinity to enable pathway. At the same time Oct-1 is expressed. It helps the activation. Oct1 is expressed in T-lymphocytes and Oct2 is induced after cell activation. NFAT has multiple family members, all of them are located in cytoplasm and signaling goes through calcineurin, NFAT
6063-552: Is involved in itchy psoriasis . Aldesleukin is a form of recombinant interleukin-2. It is manufactured using recombinant DNA technology and is marketed as a protein therapeutic and branded as Proleukin. It has been approved by the Food and Drug Administration (FDA) with a black box warning and in several European countries for the treatment of cancers ( malignant melanoma , renal cell cancer ) in large intermittent doses and has been extensively used in continuous doses. Interking
6192-530: Is mediated by transmembrane proteins known as toll-like receptors (TLRs). TLRs share a typical structural motif, the leucine rich repeats (LRRs) , which give them a curved shape. Toll-like receptors were first discovered in Drosophila and trigger the synthesis and secretion of cytokines and activation of other host defense programs that are necessary for both innate or adaptive immune responses. Ten toll-like receptors have been described in humans. Cells in
6321-459: Is one of the first responses of the immune system to infection, but it can appear without known cause. Interleukin 2 1IRL , 1M47 , 1M48 , 1M49 , 1M4A , 1M4B , 1M4C , 1NBP , 1PW6 , 1PY2 , 1QVN , 1Z92 , 2B5I , 2ERJ , 3QAZ , 3QB1 , 3INK , 4NEJ , 4NEM 3558 16183 ENSG00000109471 ENSMUSG00000027720 P60568 P04351 NM_000586 NM_008366 NP_000577 NP_032392 Interleukin-2 ( IL-2 )
6450-461: Is particularly important historically, as it is the first type I cytokine that was cloned, the first type I cytokine for which a receptor component was cloned, and was the first short-chain type I cytokine whose receptor structure was solved. Many general principles have been derived from studies of this cytokine including its being the first cytokine demonstrated to act in a growth factor–like fashion through specific high-affinity receptors, analogous to
6579-643: Is shared by all family members. The IL-2 receptor (IL-2R) α subunit binds IL-2 with low affinity (K d ~ 10 M). Interaction of IL-2 and CD25 alone does not lead to signal transduction due to its short intracellular chain but has the ability (when bound to the β and γ subunit) to increase the IL-2R affinity 100-fold. Heterodimerization of the β and γ subunits of IL-2R is essential for signalling in T cells . IL-2 can signalize either via intermediate-affinity dimeric CD122/CD132 IL-2R (K d ~ 10 M) or high-affinity trimeric CD25/CD122/CD132 IL-2R (K d ~ 10 M). Dimeric IL-2R
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#17328869040416708-449: Is tightly regulated and functions as part of both transient positive and negative feedback loops in mounting and dampening immune responses. Through its role in the development of T cell immunologic memory, which depends upon the expansion of the number and function of antigen-selected T cell clones, it plays a key role in enduring cell-mediated immunity . IL-2 has been discovered in all classes of jawed vertebrates, including sharks, at
6837-504: Is to generate active forms of the inflammatory cytokines IL-1β and IL-18. The complement system is a biochemical cascade that attacks the surfaces of foreign cells. It contains over 20 different proteins and is named for its ability to "complement" the killing of pathogens by antibodies . Complement is the major humoral component of the innate immune response. Many species have complement systems, including non- mammals like plants, fish, and some invertebrates . In humans, this response
6966-421: Is used, affected by cancer type, response to treatment and general patient health. Patients are typically treated for five consecutive days, three times a day, for fifteen minutes. The following approximately 10 days help the patient to recover between treatments. IL-2 is delivered intravenously on an inpatient basis to enable proper monitoring of side effects. A lower dose regimen involves injection of IL-2 under
7095-584: Is vascular leak syndrome (VLS; also termed capillary leak syndrome ). It is caused by lung endothelial cells expressing high-affinity IL-2R. These cells, as a result of IL-2 binding, causes increased vascular permeability. Thus, intravascular fluid extravasate into organs, predominantly lungs, which leads to life-threatening pulmonary or brain oedema. Other drawbacks of IL-2 cancer immunotherapy are its short half-life in circulation and its ability to predominantly expand regulatory T cells at high doses. Intralesional IL-2 used to treat in-transit melanoma metastases
7224-402: The "professional" phagocytes ( macrophages , neutrophils , and dendritic cells ). These cells identify and eliminate pathogens, either by attacking larger pathogens through contact or by engulfing and then killing microorganisms. The other cells involved in the innate response include innate lymphoid cells , mast cells , eosinophils , basophils , and natural killer cells . Phagocytosis
7353-513: The CXCL8 gene . IL-8 is initially produced as a precursor peptide of 99 amino acids which then undergoes cleavage to create several active IL-8 isoforms. In culture, a 72 amino acid peptide is the major form secreted by macrophages. There are many receptors on the surface membrane capable of binding IL-8; the most frequently studied types are the G protein-coupled serpentine receptors CXCR1 and CXCR2 . Expression and affinity for IL-8 differs between
7482-414: The complement system . Jawed vertebrates , including humans, have even more sophisticated defense mechanisms, including the ability to adapt to recognize pathogens more efficiently. Adaptive (or acquired) immunity creates an immunological memory leading to an enhanced response to subsequent encounters with that same pathogen. This process of acquired immunity is the basis of vaccination . Dysfunction of
7611-573: The endothelial cell surface and catecholamines affecting β-adrenergic receptors (βARs). The number of neutrophils in the blood increases and remains raised for up to six hours and immature forms are present. Although the increase in neutrophils (" neutrophilia ") is similar to that seen during bacterial infections, after exercise the cell population returns to normal by around 24 hours. The number of circulating lymphocytes (mainly natural killer cells ) decreases during intense exercise but returns to normal after 4 to 6 hours. Although up to 2% of
7740-449: The exoskeleton of insects, the shells and membranes of externally deposited eggs, and skin are examples of mechanical barriers that are the first line of defense against infection. Organisms cannot be completely sealed from their environments, so systems act to protect body openings such as the lungs , intestines , and the genitourinary tract . In the lungs, coughing and sneezing mechanically eject pathogens and other irritants from
7869-442: The hippocampus are also known to be involved in the development of spatial memories in mice. The name "interleukin" was chosen in 1979, to replace the various different names used by different research groups to designate interleukin 1 (lymphocyte activating factor, mitogenic protein, T-cell replacing factor III, B-cell activating factor, B-cell differentiation factor, and "Heidikine") and interleukin 2 (TSF, etc.). This decision
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#17328869040417998-458: The innate immune system , such as dendritic cells, macrophages, monocytes, neutrophils, and epithelial cells, to identify two classes of molecules: pathogen-associated molecular patterns (PAMPs), which are associated with microbial pathogens , and damage-associated molecular patterns (DAMPs), which are associated with components of host's cells that are released during cell damage or cell death. Recognition of extracellular or endosomal PAMPs
8127-492: The lymphoid lineage . These cells are defined by the absence of antigen-specific B- or T-cell receptor (TCR) because of the lack of recombination activating gene . ILCs do not express myeloid or dendritic cell markers. Natural killer cells (NK cells) are lymphocytes and a component of the innate immune system that does not directly attack invading microbes. Rather, NK cells destroy compromised host cells, such as tumor cells or virus-infected cells, recognizing such cells by
8256-627: The nervous systems. The immune system also plays a crucial role in embryogenesis (development of the embryo), as well as in tissue repair and regeneration . Hormones can act as immunomodulators , altering the sensitivity of the immune system. For example, female sex hormones are known immunostimulators of both adaptive and innate immune responses. Some autoimmune diseases such as lupus erythematosus strike women preferentially, and their onset often coincides with puberty . By contrast, male sex hormones such as testosterone seem to be immunosuppressive . Other hormones appear to regulate
8385-514: The respiratory tract . The flushing action of tears and urine also mechanically expels pathogens, while mucus secreted by the respiratory and gastrointestinal tract serves to trap and entangle microorganisms . Chemical barriers also protect against infection. The skin and respiratory tract secrete antimicrobial peptides such as the β- defensins . Enzymes such as lysozyme and phospholipase A2 in saliva , tears, and breast milk are also antibacterials . Vaginal secretions serve as
8514-418: The thymus , where T cells mature, it prevents autoimmune diseases by promoting the differentiation of certain immature T cells into regulatory T cells , which suppress other T cells that are otherwise primed to attack normal healthy cells in the body. IL-2 enhances activation-induced cell death (AICD) . IL-2 also promotes the differentiation of T cells into effector T cells and into memory T cells when
8643-399: The B cell surface and recognizes native (unprocessed) antigen without any need for antigen processing . Such antigens may be large molecules found on the surfaces of pathogens, but can also be small haptens (such as penicillin) attached to carrier molecule. Each lineage of B cell expresses a different antibody, so the complete set of B cell antigen receptors represent all the antibodies that
8772-496: The IgG1 and IgE isotypes. Interleukin 5 (IL5), also known as eosinophil differentiation factor (EDF), is a lineage-specific cytokine for eosinophilpoiesis. It regulates eosinophil growth and activation, and thus plays an important role in diseases associated with increased levels of eosinophils, including asthma. IL5 has a similar overall fold to other cytokines (e.g., IL2, IL4 and GCSF), but while these exist as monomeric structures, IL5
8901-587: The T cell's surface, such as CD40 ligand (also called CD154 ), which provide extra stimulatory signals typically required to activate antibody-producing B cells. Gamma delta T cells (γδ T cells) possess an alternative T-cell receptor (TCR) as opposed to CD4+ and CD8+ (αβ) T cells and share the characteristics of helper T cells, cytotoxic T cells and NK cells. The conditions that produce responses from γδ T cells are not fully understood. Like other 'unconventional' T cell subsets bearing invariant TCRs, such as CD1d -restricted natural killer T cells , γδ T cells straddle
9030-565: The antibody that recognizes this antigen. These antibodies circulate in blood plasma and lymph , bind to pathogens expressing the antigen and mark them for destruction by complement activation or for uptake and destruction by phagocytes . Antibodies can also neutralize challenges directly, by binding to bacterial toxins or by interfering with the receptors that viruses and bacteria use to infect cells. Newborn infants have no prior exposure to microbes and are particularly vulnerable to infection. Several layers of passive protection are provided by
9159-453: The body can manufacture. When B or T cells encounter their related antigens they multiply and many "clones" of the cells are produced that target the same antigen. This is called clonal selection . Both B cells and T cells carry receptor molecules that recognize specific targets. T cells recognize a "non-self" target, such as a pathogen, only after antigens (small fragments of the pathogen) have been processed and presented in combination with
9288-585: The body in pursuit of invading pathogens. Neutrophils are normally found in the bloodstream and are the most abundant type of phagocyte, representing 50% to 60% of total circulating leukocytes. During the acute phase of inflammation , neutrophils migrate toward the site of inflammation in a process called chemotaxis and are usually the first cells to arrive at the scene of infection. Macrophages are versatile cells that reside within tissues and produce an array of chemicals including enzymes, complement proteins , and cytokines. They can also act as scavengers that rid
9417-440: The body of worn-out cells and other debris and as antigen-presenting cells (APCs) that activate the adaptive immune system. Dendritic cells are phagocytes in tissues that are in contact with the external environment; therefore, they are located mainly in the skin, nose, lungs, stomach, and intestines. They are named for their resemblance to neuronal dendrites , as both have many spine-like projections. Dendritic cells serve as
9546-654: The border between innate and adaptive immunity. On one hand, γδ T cells are a component of adaptive immunity as they rearrange TCR genes to produce receptor diversity and can also develop a memory phenotype. On the other hand, the various subsets are also part of the innate immune system, as restricted TCR or NK receptors may be used as pattern recognition receptors . For example, large numbers of human Vγ9/Vδ2 T cells respond within hours to common molecules produced by microbes, and highly restricted Vδ1+ T cells in epithelia respond to stressed epithelial cells. A B cell identifies pathogens when antibodies on its surface bind to
9675-776: The brakes on NK cells. Inflammation is one of the first responses of the immune system to infection. The symptoms of inflammation are redness, swelling, heat, and pain, which are caused by increased blood flow into tissue. Inflammation is produced by eicosanoids and cytokines , which are released by injured or infected cells. Eicosanoids include prostaglandins that produce fever and the dilation of blood vessels associated with inflammation and leukotrienes that attract certain white blood cells (leukocytes). Common cytokines include interleukins that are responsible for communication between white blood cells; chemokines that promote chemotaxis ; and interferons that have antiviral effects, such as shutting down protein synthesis in
9804-520: The cells die most migrate from the blood to the tissues, mainly the intestines and lungs, where pathogens are most likely to be encountered. Some monocytes leave the blood circulation and migrate to the muscles where they differentiate and become macrophages . These cells differentiate into two types: proliferative macrophages, which are responsible for increasing the number of stem cells and restorative macrophages, which are involved their maturing to muscle cells. The immune system, particularly
9933-810: The cells. In some leukemias and lymphomas, malignant cells express the IL-2 receptor, so denileukin diftitox can kill them. In 1999 Ontak was approved by the U.S. Food and Drug Administration (FDA) for treatment of cutaneous T cell lymphoma (CTCL). IL-2 does not follow the classical dose-response curve of chemotherapeutics. The immunological activity of high and low dose IL-2 show sharp contrast. This might be related to different distribution of IL-2 receptors (CD25, CD122, CD132) on different cell populations, resulting in different cells that are activated by high and low dose IL-2. In general high doses are immune suppressive, while low doses can stimulate type 1 immunity. Low-dose IL-2 has been reported to reduce hepatitis C and B infection. IL-2 has been used in clinical trials for
10062-530: The clone of IL-2 mAb, IL-2 ic can selectively stimulate either CD25 (IL-2/JES6-1 complexes), or CD122 cells (IL-2/S4B6). IL-2/S4B6 immune complexes have high stimulatory activity for NK cells and memory CD8 T cells and they could thus replace the conventional IL-2 in cancer immunotherapy . On the other hand, IL-2/JES6-1 highly selectively stimulate regulatory T cells and they could be potentially useful for transplantations and in treatment of autoimmune diseases . According to an immunology textbook: "IL-2
10191-653: The components of the immune system are inactive. The ability of the immune system to respond to pathogens is diminished in both the young and the elderly , with immune responses beginning to decline at around 50 years of age due to immunosenescence . In developed countries , obesity , alcoholism , and drug use are common causes of poor immune function, while malnutrition is the most common cause of immunodeficiency in developing countries . Diets lacking sufficient protein are associated with impaired cell-mediated immunity, complement activity, phagocyte function, IgA antibody concentrations, and cytokine production. Additionally,
10320-589: The conditions in their environment, such as pH or available iron. As a result, the probability that pathogens will reach sufficient numbers to cause illness is reduced. Microorganisms or toxins that successfully enter an organism encounter the cells and mechanisms of the innate immune system. The innate response is usually triggered when microbes are identified by pattern recognition receptors , which recognize components that are conserved among broad groups of microorganisms, or when damaged, injured or stressed cells send out alarm signals, many of which are recognized by
10449-435: The cytotoxic function of NK cells and role in pathological Th1 responses, such as in inflammatory bowel disease and multiple sclerosis. Suppression of IL-12 activity in such diseases may have therapeutic benefit. On the other hand, administration of recombinant IL-12 may have therapeutic benefit in conditions associated with pathological Th2 responses. Interleukin 13 (IL-13) is a pleiotropic cytokine that may be important in
10578-404: The different roles of the two types of T cell. A third, minor subtype are the γδ T cells that recognize intact antigens that are not bound to MHC receptors. The double-positive T cells are exposed to a wide variety of self-antigens in the thymus , in which iodine is necessary for its thymus development and activity. In contrast, the B cell antigen-specific receptor is an antibody molecule on
10707-509: The expression of cytokines of both type 1 (Th1) and type 2 (Th2) immunity. As has been found in some studies on mammalian IL-2, data suggest that fish IL-2 can form homodimers and that this is an ancient property of the IL-2/15/15L-family cytokines. Homologues of IL-2 have not been reported for jawless fish (hagfish and lamprey) or invertebrates. While the causes of itchiness are poorly understood, some evidence indicates that IL-2
10836-424: The final differentiation of B cells into immunoglobulin-secreting cells, as well as inducing myeloma/plasmacytoma growth, nerve cell differentiation, and, in hepatocytes, acute-phase reactants. A number of other cytokines may be grouped with IL6 on the basis of sequence similarity. These include granulocyte colony-stimulating factor (GCSF) and myelomonocytic growth factor (MGF). GCSF acts in hematopoiesis by affecting
10965-431: The formation of a membrane attack complex . The adaptive immune system evolved in early vertebrates and allows for a stronger immune response as well as immunological memory , where each pathogen is "remembered" by a signature antigen. The adaptive immune response is antigen-specific and requires the recognition of specific "non-self" antigens during a process called antigen presentation . Antigen specificity allows for
11094-450: The four cysteines of IL-10. Interleukin 11 (IL-11) is a secreted protein that stimulates megakaryocytopoiesis, initially thought to lead to an increased production of platelets (it has since been shown to be redundant to normal platelet formation), as well as activating osteoclasts, inhibiting epithelial cell proliferation and apoptosis, and inhibiting macrophage mediator production. These functions may be particularly important in mediating
11223-460: The function of IL-2 is to stimulate the growth of helper, cytotoxic and regulatory T cells. IL-2 is a member of a cytokine family, each member of which has a four alpha helix bundle ; the family also includes IL-4 , IL-7 , IL-9 , IL-15 and IL-21 . IL-2 signals through the IL-2 receptor , a complex consisting of three chains, termed alpha ( CD25 ), beta ( CD122 ) and gamma ( CD132 ). The gamma chain
11352-419: The functions of specialized cells (located in the thymus and bone marrow) is to present young lymphocytes with self antigens produced throughout the body and to eliminate those cells that recognize self-antigens , preventing autoimmunity. Common autoimmune diseases include Hashimoto's thyroiditis , rheumatoid arthritis , diabetes mellitus type 1 , and systemic lupus erythematosus . Hypersensitivity
11481-420: The generation of responses that are tailored to specific pathogens or pathogen-infected cells. The ability to mount these tailored responses is maintained in the body by "memory cells". Should a pathogen infect the body more than once, these specific memory cells are used to quickly eliminate it. The cells of the adaptive immune system are special types of leukocytes, called lymphocytes. B cells and T cells are
11610-403: The growth and differentiation of T cells and certain B cells through the release of secreted protein factors. These factors, which include interleukin 2 (IL2), are secreted by lectin- or antigen-stimulated T cells, and have various physiological effects. IL2 is a lymphokine that induces the proliferation of responsive T cells. In addition, it acts on some B cells, via receptor-specific binding, as
11739-502: The hematopoietic, osseous and mucosal protective effects of interleukin 11. Interleukin 12 (IL-12) is a disulphide-bonded heterodimer consisting of a 35kDa alpha subunit and a 40kDa beta subunit. It is involved in the stimulation and maintenance of Th1 cellular immune responses, including the normal host defence against various intracellular pathogens, such as Leishmania, Toxoplasma, Measles virus , and Human immunodeficiency virus 1 (HIV). IL-12 also has an important role in enhancing
11868-527: The host cell. Growth factors and cytotoxic factors may also be released. These cytokines and other chemicals recruit immune cells to the site of infection and promote the healing of any damaged tissue following the removal of pathogens. The pattern-recognition receptors called inflammasomes are multiprotein complexes (consisting of an NLR, the adaptor protein ASC, and the effector molecule pro-caspase-1) that form in response to cytosolic PAMPs and DAMPs, whose function
11997-635: The immune system as well, most notably prolactin , growth hormone and vitamin D . Although cellular studies indicate that vitamin D has receptors and probable functions in the immune system, there is no clinical evidence to prove that vitamin D deficiency increases the risk for immune diseases or vitamin D supplementation lowers immune disease risk. A 2011 United States Institute of Medicine report stated that "outcomes related to ... immune functioning and autoimmune disorders , and infections ... could not be linked reliably with calcium or vitamin D intake and were often conflicting." The immune system
12126-450: The immune system can cause autoimmune diseases , inflammatory diseases and cancer . Immunodeficiency occurs when the immune system is less active than normal, resulting in recurring and life-threatening infections. In humans, immunodeficiency can be the result of a genetic disease such as severe combined immunodeficiency , acquired conditions such as HIV / AIDS , or the use of immunosuppressive medication . Autoimmunity results from
12255-448: The immune system. Conversely, non-self molecules are those recognized as foreign molecules. One class of non-self molecules are called antigens (originally named for being anti body gen erators) and are defined as substances that bind to specific immune receptors and elicit an immune response. Several barriers protect organisms from infection, including mechanical, chemical, and biological barriers. The waxy cuticle of most leaves,
12384-699: The individual's own cells, marking them for destruction. This is also called antibody-dependent (or cytotoxic) hypersensitivity, and is mediated by IgG and IgM antibodies. Immune complexes (aggregations of antigens, complement proteins, and IgG and IgM antibodies) deposited in various tissues trigger Type III hypersensitivity reactions. Type IV hypersensitivity (also known as cell-mediated or delayed type hypersensitivity ) usually takes between two and three days to develop. Type IV reactions are involved in many autoimmune and infectious diseases, but may also involve contact dermatitis . These reactions are mediated by T cells , monocytes , and macrophages . Inflammation
12513-425: The inflammatory response. They are most often associated with allergy and anaphylaxis . Basophils and eosinophils are related to neutrophils. They secrete chemical mediators that are involved in defending against parasites and play a role in allergic reactions, such as asthma . Innate lymphoid cells (ILCs) are a group of innate immune cells that are derived from common lymphoid progenitor and belong to
12642-448: The initial T cell is also stimulated by an antigen , thus helping the body fight off infections. Together with other polarizing cytokines, IL-2 stimulates naive CD4 T cell differentiation into T h 1 and T h 2 lymphocytes while it impedes differentiation into T h 17 and folicular T h lymphocytes. IL-2 increases the cell killing activity of both natural killer cells and cytotoxic T cells . Its expression and secretion
12771-497: The initiation of Th1 immune responses. During wake periods, differentiated effector cells, such as cytotoxic natural killer cells and cytotoxic T lymphocytes, peak to elicit an effective response against any intruding pathogens. Anti-inflammatory molecules, such as cortisol and catecholamines , also peak during awake active times. Inflammation would cause serious cognitive and physical impairments if it were to occur during wake times, and inflammation may occur during sleep times due to
12900-437: The innate and adaptive immune responses and help determine which immune responses the body makes to a particular pathogen. These cells have no cytotoxic activity and do not kill infected cells or clear pathogens directly. They instead control the immune response by directing other cells to perform these tasks. Helper T cells express T cell receptors that recognize antigen bound to Class II MHC molecules. The MHC:antigen complex
13029-886: The innate component, plays a decisive role in tissue repair after an insult . Key actors include macrophages and neutrophils , but other cellular actors, including γδ T cells , innate lymphoid cells (ILCs), and regulatory T cells (Tregs), are also important. The plasticity of immune cells and the balance between pro-inflammatory and anti-inflammatory signals are crucial aspects of efficient tissue repair. Immune components and pathways are involved in regeneration as well, for example in amphibians such as in axolotl limb regeneration . According to one hypothesis, organisms that can regenerate ( e.g. , axolotls ) could be less immunocompetent than organisms that cannot regenerate. Failures of host defense occur and fall into three broad categories: immunodeficiencies, autoimmunity, and hypersensitivities. Immunodeficiencies occur when one or more of
13158-433: The innate immune system have pattern recognition receptors, which detect infection or cell damage, inside. Three major classes of these "cytosolic" receptors are NOD–like receptors , RIG (retinoic acid-inducible gene)-like receptors , and cytosolic DNA sensors. Some leukocytes (white blood cells) act like independent, single-celled organisms and are the second arm of the innate immune system. The innate leukocytes include
13287-412: The integrity of the hippocampus seem to be spared. However, when mice with this genetic deletion have wild-type neural precursor cells injected into their hippocampus and these cells are allowed to mature into astrocytes containing the interleukin-1 receptors, the mice exhibit normal hippocampal-dependent memory function, and partial restoration of long-term potentiation . T lymphocytes regulate
13416-487: The level of dosing usually determines the severity of the side effects. In the case of local IL-2 application, the therapeutic window spans several orders of magnitude. Some common side effects: More serious and dangerous side effects sometimes are seen, such as breathing problems, serious infections , seizures , allergic reactions , heart problems, kidney failure or a variety of other possible complications. The most common adverse effect of high-dose IL-2 therapy
13545-423: The lifetime of an animal, these memory cells remember each specific pathogen encountered and can mount a strong response if the pathogen is detected again. T-cells recognize pathogens by small protein-based infection signals, called antigens, that bind to directly to T-cell surface receptors. B-cells use the protein, immunoglobulin, to recognize pathogens by their antigens. This is "adaptive" because it occurs during
13674-415: The lifetime of an individual as an adaptation to infection with that pathogen and prepares the immune system for future challenges. Immunological memory can be in the form of either passive short-term memory or active long-term memory. The immune system is involved in many aspects of physiological regulation in the body. The immune system interacts intimately with other systems, such as the endocrine and
13803-459: The loss of the thymus at an early age through genetic mutation or surgical removal results in severe immunodeficiency and a high susceptibility to infection. Immunodeficiencies can also be inherited or ' acquired '. Severe combined immunodeficiency is a rare genetic disorder characterized by the disturbed development of functional T cells and B cells caused by numerous genetic mutations. Chronic granulomatous disease , where phagocytes have
13932-454: The major types of lymphocytes and are derived from hematopoietic stem cells in the bone marrow . B cells are involved in the humoral immune response , whereas T cells are involved in cell-mediated immune response . Killer T cells only recognize antigens coupled to Class I MHC molecules, while helper T cells and regulatory T cells only recognize antigens coupled to Class II MHC molecules. These two mechanisms of antigen presentation reflect
14061-509: The microbe, they activate their protease activity, which in turn activates other complement proteases, and so on. This produces a catalytic cascade that amplifies the initial signal by controlled positive feedback . The cascade results in the production of peptides that attract immune cells, increase vascular permeability , and opsonize (coat) the surface of a pathogen, marking it for destruction. This deposition of complement can also kill cells directly by disrupting their plasma membrane via
14190-408: The milieu of hormones produced at this time (leptin, pituitary growth hormone, and prolactin) supports the interactions between APCs and T-cells, a shift of the T h 1/T h 2 cytokine balance towards one that supports T h 1, an increase in overall T h cell proliferation, and naïve T cell migration to lymph nodes. This is also thought to support the formation of long-lasting immune memory through
14319-412: The mother. During pregnancy, a particular type of antibody, called IgG , is transported from mother to baby directly through the placenta , so human babies have high levels of antibodies even at birth, with the same range of antigen specificities as their mother. Breast milk or colostrum also contains antibodies that are transferred to the gut of the infant and protect against bacterial infections until
14448-462: The negative consequences of sleep deprivation, sleep and the intertwined circadian system have been shown to have strong regulatory effects on immunological functions affecting both innate and adaptive immunity. First, during the early slow-wave-sleep stage, a sudden drop in blood levels of cortisol , epinephrine , and norepinephrine causes increased blood levels of the hormones leptin , pituitary growth hormone , and prolactin . These signals induce
14577-506: The newborn can synthesize its own antibodies. This is passive immunity because the fetus does not actually make any memory cells or antibodies—it only borrows them. This passive immunity is usually short-term, lasting from a few days up to several months. In medicine, protective passive immunity can also be transferred artificially from one individual to another. When B cells and T cells are activated and begin to replicate, some of their offspring become long-lived memory cells. Throughout
14706-452: The organism. If a pathogen breaches these barriers, the innate immune system provides an immediate, but non-specific response. Innate immune systems are found in all animals . If pathogens successfully evade the innate response, vertebrates possess a second layer of protection, the adaptive immune system , which is activated by the innate response. Here, the immune system adapts its response during an infection to improve its recognition of
14835-507: The pathogen. This improved response is then retained after the pathogen has been eliminated, in the form of an immunological memory , and allows the adaptive immune system to mount faster and stronger attacks each time this pathogen is encountered. Both innate and adaptive immunity depend on the ability of the immune system to distinguish between self and non-self molecules . In immunology, self molecules are components of an organism's body that can be distinguished from foreign substances by
14964-434: The presence of melatonin . Inflammation causes a great deal of oxidative stress and the presence of melatonin during sleep times could actively counteract free radical production during this time. Physical exercise has a positive effect on the immune system and depending on the frequency and intensity, the pathogenic effects of diseases caused by bacteria and viruses are moderated. Immediately after intense exercise there
15093-475: The production, differentiation, and function of two related white cell groups in the blood. MGF also acts in hematopoiesis, stimulating proliferation and colony formation of normal and transformed avian cells of the myeloid lineage. Cytokines of the IL6/GCSF/MGF family are glycoproteins of about 170 to 180 amino acid residues that contain four conserved cysteine residues involved in two disulphide bonds. They have
15222-472: The proliferation of T lymphocytes, which requires interaction of IL-15 with IL-15R alpha and components of IL-2R, including IL-2R beta and IL-2R gamma (common gamma chain, γc), but not IL-2R alpha. Interleukin 17 (IL-17) is a potent proinflammatory cytokine produced by activated memory T cells. This cytokine is characterized by its proinflammatory properties, role in recruiting neutrophils, and importance in innate and adaptive immunity. Not only does IL-17 play
15351-399: The regulation of the inflammatory and immune responses. It inhibits inflammatory cytokine production and synergises with IL-2 in regulating interferon-gamma synthesis. The sequences of IL-4 and IL-13 are distantly related. Interleukin 15 (IL-15) is a cytokine that possesses a variety of biological functions, including stimulation and maintenance of cellular immune responses. IL-15 stimulates
15480-529: The same 12-stranded beta-sheet structure as both the heparin binding growth factors and the Kunitz-type soybean trypsin inhibitors. The beta-sheets are arranged in 4 similar lobes around a central axis, 8 strands forming an anti-parallel beta-barrel. Several regions, especially the loop between strands 4 and 5, have been implicated in receptor binding. Molecular cloning of the Interleukin 1 Beta converting enzyme
15609-532: The same receptors as those that recognize pathogens. Innate immune defenses are non-specific, meaning these systems respond to pathogens in a generic way. This system does not confer long-lasting immunity against a pathogen. The innate immune system is the dominant system of host defense in most organisms, and the only one in plants. Cells in the innate immune system use pattern recognition receptors to recognize molecular structures that are produced by pathogens. They are proteins expressed, mainly, by cells of
15738-477: The skin typically on an outpatient basis. It may alternatively be given on an inpatient basis over 1–3 days, similar to and often including the delivery of chemotherapy . Intralesional IL-2 is commonly used to treat in-transit melanoma metastases and has a high complete response rate. In preclinical and early clinical studies, local application of IL-2 in the tumor has been shown to be clinically more effective in anticancer therapy than systemic IL-2 therapy, over
15867-470: The soluble IL-1 receptor is thought to be post-translationally derived from cleavage of the extracellular portion of the membrane receptors. Both IL-1 receptors ( CD121a/IL1R1 , CD121b/IL1R2 ) appear to be well conserved in evolution, and map to the same chromosomal location. The receptors can both bind all three forms of IL-1 (IL-1 alpha, IL-1 beta and IL-1 receptor antagonist ). The crystal structures of IL1A and IL1B have been solved, showing them to share
15996-433: The systemic dose of IL-2 is too low to cause side effects, since the total dose is about 100 to 1000 fold lower. Clinical studies showed painful injections at the site of radiation as the most important side effect, reported by patients. In the case of irradiation of nasopharyngeal carcinoma the five-year disease-free survival increased from 8% to 63% by local IL-2 therapy Systemic IL-2 has a narrow therapeutic window , and
16125-503: The target cell's plasma membrane , allowing ions , water and toxins to enter. The entry of another toxin called granulysin (a protease) induces the target cell to undergo apoptosis . T cell killing of host cells is particularly important in preventing the replication of viruses. T cell activation is tightly controlled and generally requires a very strong MHC/antigen activation signal, or additional activation signals provided by "helper" T cells (see below). Helper T cells regulate both
16254-401: The three pathways include bcl-6 (the PI3K/Akt/mTOR pathway), CD25 & prdm-1 (the JAK-STAT pathway) and certain cyclins (the MAPK/ERK pathway). Gene expression regulation for IL-2 can be on multiple levels or by different ways. One of the checkpoints (in other words one of the things which needs to be done before IL-2 is expressed) is that there must be signaling through a conjunction of
16383-626: The treatment of chronic viral infections and as a booster (adjuvant) for vaccines. The use of large doses of IL-2 given every 6–8 weeks in HIV therapy, similar to its use in cancer therapy, was found to be ineffective in preventing progression to an AIDS diagnosis in two large clinical trials published in 2009. More recently low dose IL-2 has shown early success in modulating the immune system in disease like type 1 diabetes and vasculitis. There are also promising studies looking to use low dose IL-2 in ischaemic heart disease. IL-2 cannot accomplish its role as
16512-483: The two receptors (CXCR1 > CXCR2). Through a chain of biochemical reactions, IL-8 is secreted and is an important mediator of the immune reaction in the innate immune system response. Interleukin 9 (IL-9) is a cytokine that supports IL-2 independent and IL-4 independent growth of helper T cells. Early studies had indicated that Interleukin 9 and 7 seem to be evolutionary related and Pfam, InterPro and PROSITE entries exist for interleukin 7/interleukin 9 family. However,
16641-591: Was taken during the Second International Lymphokine Workshop in Switzerland (27–31 May 1979 in Ermatingen ). The term interleukin derives from ( inter- ) "as a means of communication", and ( -leukin ) "deriving from the fact that many of these proteins are produced by leukocytes and act on leukocytes". The name is something of a relic; it has since been found that interleukins are produced by
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