CD278

ICOS
Identifiers
Aliases	ICOS, AILIM, CD278, CVID1, inducible T-cell co-stimulator, inducible T-cell costimulator
External IDs	OMIM: 604558 MGI: 1858745 HomoloGene: 8097 GeneCards: ICOS
Gene ontology Molecular function • phosphatidylinositol-4,5-bisphosphate 3-kinase activity Cellular component • integral component of membrane • extracellular region • plasma membrane • integral component of plasma membrane • membrane • external side of plasma membrane • intracellular Biological process • T cell tolerance induction • single organismal cell-cell adhesion • T cell costimulation • immune response • regulation of phosphatidylinositol 3-kinase signaling • phosphatidylinositol phosphorylation • phosphatidylinositol-mediated signaling Sources:Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	29851	54167
Ensembl	ENSG00000163600	ENSMUSG00000026009
UniProt	Q9Y6W8	Q9WVS0
RefSeq (mRNA)	NM_012092	NM_017480
RefSeq (protein)	NP_036224	NP_059508
Location (UCSC)	Chr 2: 203.94 – 203.96 Mb	Chr 1: 60.98 – 61 Mb
PubMed search

29851

54167

ENSG00000163600

ENSMUSG00000026009

Q9Y6W8

Q9WVS0

NM_012092

NM_017480

NP_036224

NP_059508

Inducible T-cell costimulator is an immune checkpoint protein that in humans is encoded by the ICOS gene.

CD278 or ICOS (Inducible T-cell COStimulator) is a CD28-superfamily costimulatory molecule that is expressed on activated T cells. It is thought to be important for T_h2 cells in particular.

The protein encoded by this gene belongs to the CD28 and CTLA-4 cell-surface receptor family. It forms homodimers and plays an important role in cell-cell signaling, immune responses and regulation of cell proliferation.

Compared to wild-type naïve T cells, ICOS-/- T cells activated with plate-bound anti-CD3 have reduced proliferation and IL-2 secretion. The defect in proliferation can be rescued by addition of IL-2 to the culture, suggesting the proliferative defect is due either to ICOS-mediated IL-2 secretion or the activation of similar signaling pathways between ICOS and IL-2. In terms of Th1 and Th2 cytokine secretion, ICOS-/- CD4+ T cell activated in vitro reduced IL-4 secretion, while maintaining similar IFN-g secretion. Similarly, CD4+ T cells purified from ICOS-/- mice immunized with the protein keyhole limpet hemocyanin (KLH) in alum or complete Freund's Adjuvant have attenuated IL-4 secretion, but similar IFN-g and IL-5 secretion when recalled with KLH.

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