ICOSLG
ICOS ligand is a protein that in humans is encoded by the ICOSLG gene located at chromosome 21. ICOSLG has also been designated as CD275 (cluster of differentiation 275).
| ICOSLG | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Aliases | ICOSLG, B7-H2, B7H2, B7RP-1, B7RP1, CD275, GL50, ICOS-L, ICOSL, LICOS, inducible T-cell co-stimulator ligand, inducible T-cell costimulator ligand, inducible T cell costimulator ligand, B7h | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 605717 MGI: 1354701 HomoloGene: 49412 GeneCards: ICOSLG | ||||||||||||||||||||||||||||||||||||||||||||||||||
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ICOSLG is glycosylated transmembrane structure, which is classified as a member of the B7 family due to the significant homology with B7 family members. The B7/CD28 superfamily provides both positive and negative co-signals to immunocytes in immune responses.
The interaction of ICOSLG with ICOS, the specific receptor for ICOSLG, is critically involved in the activation, proliferation, differentiation and cytokine production of T cells as well as in the antibody secretion from B cells during secondary immune responses.
ICOSLG, which is extensively expressed in both non-lymphatic and lymphatic tissues, is an important molecule in upregulating and promoting T cell immune responses. Expression of ICOSLG in naive B cells and monocytes in PBMCs is at a low level. After stimulation by IFN-γ, TNF-α, or LPS, it can be quickly up-regulated. The induced expression of ICOS on activated T cells mainly regulates the secretion of Th2 cytokines and thus shifts the immune response to the Th2 type. It has been reported that the ICOS/ICOSLG pathway is involved in immunopathogenesis such as infection, hypersensitivity, autoimmune diseases, transplantation immunity and tumor immunity.
ICOSLG is also a major costimulator in endothelial cell-mediated T cell activation. It has an important physiological role of ICOSLG in the reactivation of effector/memory T cells on the endothelium controlling the entry of immune cells into inflamed tissue.