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Interleukin-18 receptor accessory protein (IL18RAP), belongs to the IL-1 family of cytokines which holds multiple immunoregulatory functions. It has been found that IL18RAP does not mediate IL18-binding, however, IL18RAP is involved in IL18-dependent signal transduction, which leads to NF-kappa-B and JNK activation. IL18R1 as well as IL18RAP polymorphisms have been linked with the following diseases: schizophrenia, HSV1 seropositivity and atopic asthma.

IL13 is an immunoregulatory cytokine produced primarily by activated Th2 cells. IL-13 is involved in several stages of B-cell maturation and differentiation. It up-regulates CD23 and MHC class II expression, and promotes IgE isotype switching of B cells. This cytokine down-regulates macrophage activity, thereby inhibits the production of pro-inflammatory cytokines and chemokines. This cytokine is found to be critical to the pathogenesis of allergen-induced asthma but operates through mechanisms independent of IgE and eosinophils. This gene, IL3, IL5, IL4, and CSF2 form a cytokine gene cluster on chromosome 5q, with this gene particularly close to IL4.

IL13 is an immunoregulatory cytokine produced primarily by activated Th2 cells. IL-13 is involved in several stages of B-cell maturation and differentiation. It up-regulates CD23 and MHC class II expression, and promotes IgE isotype switching of B cells. This cytokine down-regulates macrophage activity, thereby inhibits the production of pro-inflammatory cytokines and chemokines. This cytokine is found to be critical to the pathogenesis of allergen-induced asthma but operates through mechanisms independent of IgE and eosinophils. This gene, IL3, IL5, IL4, and CSF2 form a cytokine gene cluster on chromosome 5q, with this gene particularly close to IL4.

IL-16 is a pleiotropic cytokine that functions as a chemoattractant, a modulator of T cell activation, and an inhibitor of HIV replication. The signaling process of IL-16 is mediated by CD4. The product of this gene undergoes proteolytic processing, which is found to yield two functional proteins. IL-16 functions exclusively attributed to the secreted C-terminal peptide, while the N-terminal product may play a role in cell cycle control. Caspase 3 is reported to be involved in the proteolytic processing of this protein. Two transcript variants encoding different isoforms have been found for this gene.
IL-16 stimulates a migratory response in cd4+ lymphocytes, monocytes, and eosinophils. Also induces t-lymphocyte expression of interleukin 2 receptor, ligand for cd4.

IL20 is a cytokine structurally related to interleukin 10 (IL10). IL20 cytokine has been shown to transduce its signal through signal transducer and activator of transcription 3 (STAT3) in keratinocytes. A specific receptor for this cytokine is found to be expressed in skin and upregulated dramatically in psoriatic skin, suggesting a role for this protein in epidermal function and psoriasis.

Interleukin 33 (IL-33) is a 32kDa proinflammatory cytokine that may also regulate gene transcription in producer cells. IL-33 is structurally related to IL-1, which induces helper T cells to produce type 2 cytokines and acts through the receptor IL1RL-1 (IL1 receptor-like-1), which is known also as ST2. Binding of IL-33 to this receptor activates NF-kappa-B and MAP kinases and induces in vitro Th2 cells to produce cytokines. In vivo, IL-33 induces expression of IL-4, IL-5, IL-13 and leads to severe pathological changes in mucosal organs and in vitro, it can be divided to N-terminal fragment of 12kDa and C-terminal fragment of 18kDa by cleavage of caspase-1.

CD48, is a GPI-linked protein which belongs to the CD2 family of immunoglobulin superfamily molecules. CD48 is capable to transduce signals and can likewise trigger signaling through CD2 or 2B4. CD48 to CD2 interactions advocate T cell activation and class replacing to IgG2a in B cells. In addition, high affinity of CD48 to 2B4, interactions may either promote or inhibit NK cell as well as cytotoxic T cell (CTL) activation. CD48 does not contain a transmembrane domain, though it is held at the cell surface by a GPI anchor through a C-terminal domain which possibly split to produce a soluble form of the receptor.

CD200R1, also known as cell surface glycoprotein CD200 receptor 1, is an isoform of CD200 receptors which is expressed on cells of the myeloid lineage. CD200R1 inhibitory signaling pathway has been involved in taking a prominent role in limiting inflammation in a broad range of inflammatory diseases. CD200R1 signaling inhibits the expression of proinflammatory molecules including tumor necrosis factor, interferons, in addition to inducible nitric oxide synthase in response to selected stimuli.

IL-17 family members are glycoproteins secreted as dimers which induce local cytokine production and recruit granulocytes to sites of inflammation. The IL-17 family is comprised of at least six pro-inflammatory cytokines that share a conserved cysteine-knot structure but diverge at the N-terminus. IL-17 is induced by IL-15 and IL-23, mostly in activated CD4+ T cells distinct from Th1 or Th2 cells. IL-17B binds the IL-17B receptor, but not the IL-17 receptor; it is most homologous with IL-17D, which is expressed by resting CD4+ T cells and CD19+ B cells. IL17B Diseases associated with IL17B include spondyloarthropathy, and neuronitis, and among its related super-pathways are Mucin expression in CF via IL-6, IL-17 signaling pathways and STAT3 Pathway.

IL-21 is produced by CD4+ T cells in response to antigenic stimulation. Its action enhances antigen-specific responses of immune cells. The biological effects of IL-21 include induction of differentiation of T-cells-stimulated B-cells into plasma cells and memory B-cells, stimulation (in conjuction) with IL-4 of IgG production, and induction of apoptotic effects in naive B-cells and stimulated B-cells in the absence of T-cell signaling. Additionally, IL-21 promotes the anti-tumor activity of CD8+ T-cells and NK cells. IL-21 exerts its effect through binding to a specific type I cytokine receptor, IL-21R, which also contains the gamma chain (°C) found in other cytokine receptors including IL-2, IL-4, IL-7, IL-9 and IL-15. The IL-21/IL-21R interaction triggers a cascade of events which includes activation of the tyrosine kinases JAK1 and JAK3, followed by activation of the transcription factors STAT1 and STAT3.

IL4 is a pleiotropic cytokine produced by activated T cells. IL4 is a ligand for interleukin 4 receptor. The interleukin 4 receptor also binds to IL13, which may contribute to many overlapping functions of this cytokine and IL13. STAT6, a signal transducer and activator of transcription, has been shown to play a central role in mediating the immune regulatory signal of this cytokine. This gene, IL3, IL5, IL13, and CSF2 form a cytokine gene cluster on chromosome 5q, with this gene particularly close to IL13. IL4, IL13 and IL5 are found to be regulated coordinately by several long-range regulatory elements in an over 120 kilobase range on the chromosome. Two alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported.

FLT3 ligand is a receptor for the fl cytokine has a tyrosine-protein kinase activity & a growth factor that regulates proliferation of early hematopoietic cells. Flt3-Ligand synergizes with other CSFs and interleukins to induce growth and differentiation.

CD33 is putative adhesion molecule of myelomonocytic-derived cells which mediates sialic-acid dependent binding to cells. CD33 prefers to bind to alpha-2,6-linked sialic acid. The sialic acid recognition site is masked by cis interactions with sialic acids on the same cell surface. In the immune response, CD33 perform as an inhibitory receptor upon ligand induced tyrosine phosphorylation by recruiting cytoplasmic phosphatases through their SH2 domains which block signal transduction through dephosphorylation of signaling molecules. In addition, CD33 induces apoptosis in acute myeloid leukemia.

Macrophage Inflammatory Proteins (MIP) belong to the family of chemotactic cytokines known as chemokines. In humans, there are two major forms, MIP-1a and MIP-1b that are now officially named CCL3 and CCL4 respectively. Both are major factors produced by macrophages after they are stimulated with bacterial endotoxins. They activate human granulocytes (neutrophils, eosinophils and basophils) which can lead to acute neutrophilic inflammation. They also induce the synthesis and release of other pro-inflammatory cytokines such as interleukin 1 (IL-1), IL-6 and TNF-a from fibroblasts and macrophages. The genes for CCL3 and CCL4 are both located on human chromosome 17.

CTLA-4 is a member of the immunoglobulin superfamily and encodes a protein which transmits an inhibitory signal to T cells. The protein contains a V domain, a transmembrane domain, and a cytoplasmic tail. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. The membrane-bound isoform functions as a homodimer interconnected by a disulfide bond, while the soluble isoform functions as a monomer. Mutations in this gene have been associated with insulin-dependent diabetes mellitus, Graves disease, Hashimoto thyroiditis, celiac disease, systemic lupus erythematosus, thyroid-associated orbitopathy, and other autoimmune diseases.

CXC chemokine ligand 16 (CXCL16) is a type I membrane protein, which contains a non-ELR motif-containing CXC chemokine domain in its extracellular region. Human and Mouse CXCL16 share a 70% a.a. sequence similarity within their chemokine domains and 49% overall a.a. sequence identity. Functional CXCL16 can be dropped from the cell surface as an approximately 35kDa soluble protein. CXCR6 is the functional receptor for CXCL16. CXCL16 functions as a scavenger receptor on macrophages, which specifically binds to OxLDL (oxidized low density lipoprotein), proposing that CXCL16 may be involved in pathophysiology such as atherogenesis. In addition, CXCL16 induces a strong chemotactic response and calcium mobilization. CXCL16 binds to CXCR6/Bonzo.

Chemokine (C-X-C motif) ligand (CXCL7) is a small cytokine belonging to the CXC chemokine family. It is a protein that is released in large amounts from platelets following their activation. It stimulates various processes including mitogenesis, synthesis of extracellular matrix, glucose metabolism and synthesis of plasminogen activator.

Chemokine (C-X-C motif) ligand 11 (CXCL11) is a small cytokine belonging to the CXC chemokinen family. I-TAC is highly expressed in peripheral blood leukocytes, pancreas and liver, with moderate levels in thymus, spleen and lung and low expression levels were in small intestine, placenta and prostate. Gene expression of CXCL11 is strongly induced by IFN-g and IFN-b, and weakly induced by IFN-a. The I-TACchemokine elicits its effects on its target cells by interacting with the cell surface chemokine receptor CXCR3, with a higher affinity than do the other ligands for this receptor, CXCL9 and CXCL10. I-TAC is chemotactic for activated T cells.The CXCL11 gene is located on human chromosome 4 along with many other members of the CXC chemokine family.

BCA-1 is a CXC chemokine that is highly expressed in thesecondary lymphoid organs, such as follicles of the spleen, lymph nodes, and Peyer's patches. CXCL13 promotes the migration of B lymphocytes (compared to T cells and macrophages), by stimulating calcium influx into, and chemotaxis of, cells expressing Burkitt's lymphoma receptor 1 (BLR1). BCA1 therefore function in the homing of B lymphocytes to follicles. Human BCA-1 shares a 64% amino acid sequence similarity with the mouse protein and 23 - 34% amino acid sequence identity with other known CXC chemokines. Recombinant or chemically synthesized BCA1 is a potent chemoattractant for B lymphocytes but not T lymphocytes, monocytes or neutrophils. BLR1, a G protein-coupled receptor originally isolated from Burkitt’s lymphoma cells, has now been shown to be the specific receptor for BCA1. Among cells of the hematopoietic lineages, the expression of BLR-1, now designated CXCR-5, is restricted to B lymphocytes and a subpopulation of T helper memory cells.

Chemokine (C-C motif) ligand 11 (CCL11) is a small cytokine belonging to the CC chemokine family that is also known as eotaxin. CCL11 selectively recruits eosinophils by inducing their chemotaxis, and therefore, is implicated in allergic responses. The effects of CCL11 are mediated by its binding to a G-protein-linked receptor known as a chemokine receptor. Chemokine receptors for which CCL11 is a ligand include CCR2, CCR3 and CCR5. The gene for human CCL11 (scya11) is encoded on three exons and is located on chromosome 17.

CCL3L1 is a small cytokine that belongs to the CC chemokines. The CCL3L1 gene is one of several cytokine genes clustered on the q-arm of chromosome 17. CCL3L1 is involved in immunoregulatory and inflammatory processes. CCL3L1 binds to several chemokine receptors including CCBP2 and CCR5. CCR5 is a co-receptor for HIV, and binding of the CCL3L1 protein to CCR5 inhibits HIV entry.

Granulocyte Chemotactic Protein 2 (CXCL6), also known as GCP-2, is a Chemotactic for neutrophil granulocytes. GCP-2 signals through binding and activation of its receptors (CXCR1 and CXCR2). GCP-2 has strong antibacterial activity against Gram-positive and Gram-negative bacteria In addition to its chemotactic and angiogenic property.

Chemokine (C-X-C motif) ligand 3 (CXCL3) is a small cytokine belonging to the CXC chemokine family that is also known as GRO3 oncogene (GRO3), GRO protein gamma (GROg) and macrophage inflammatory protein-2-beta (MIP2b). CXCL3 controls migration and adhesion of monocytes and mediates it effects on its target cell by interacting with a cell surface chemokine receptor called CXCR2. The gene for CXCL3 is located on chromosome 4 in a cluster of other CXC chemokines.

Chemokine (C-C motif) ligand 2 (CCL2) is a small cytokine belonging to the CC chemokine family that is also known as monocyte chemotactic protein-1 (MCP-1). It is found at the site of tooth eruption and bone degradation. In the bone, CCL2 is expressed by mature osteoclasts and osteoblasts and is under the control of nuclear factor ?B (NF?B). CCL2 recruits immune cells, such as monocytes, to sites of tissue injury and infection. This chemokine is produced as a protein precursor containing signal peptide of 23 amino acids and a mature peptide of 76 amino acids. It is a monomeric polypeptide, with a molecular weightof approximately 13kDa. As with many other CC chemokines, CCL2 is located on chromosome 17 in humans. The cell surface receptors that bind CCL2 are CCR2 and CCR5.