TIM3 (HAVCR2) is a cell surface receptor implicated in modulating innate and adaptive immune responses. It is generally accepted to have an inhibiting function. Reports on stimulating functions suggest that the activity may be influenced by the cellular context and/or the respective ligand. TIM3 regulates macrophage activation, inhibits T-helper type 1 lymphocyte (Th1)-mediated auto- and alloimmune responses, and promotes immunological tolerance. In CD8+ cells TIM3 attenuates TCR-induced signaling, specifically by blocking NF-kappaB and NFAT promoter activities resulting in the loss of IL-2 secretion. [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/Q8TDQ0].