Update on ICOS: A Possible Target for Turning-Off Autoimmunity

Inducible Co-stimulator (ICOS) is one of the co-stimulatory molecules that are unregulated within hours after TCR engagement. The interaction between ICOS and its ligand ICOSL positively co-stimulates T cell activation and proliferation. Thus, ICOS/ICOSL pathway contributes to one of the predisposing factors for autoimmune condition. Therefore, the positive co-stimulatory properties of ICOS are now being regarded as a possible and potential target for treating autoimmune disorders. Several in vivo studies have confirmed the amelioration of autoimmune disease by targeting ICOS pathway. This mini-review comprehensively describes the updated issues regarding ICOS from their discovery and functional consequences (at both genetic and protein aspects) to the recent patents in targeting ICOS pathway for turning-off immune responses in autoimmunity.