As a member of the T cell immunoglobulin and mucin domain (TIM) family, Tim-3 is reported to promote or terminate Th1 immunity and is thought to influence a range of inflammatory conditions. It is constitutively expressed in a subset of murine IFNgamma-secreting Th1 cells, but not Th2 cells, in both human and mice. Additionally, Tim-3 is expressed dendritic cells, and by a subset of CD4+ cells where its levels of expression increase upon anti-CD3/28 stimulation. This molecule is also highly expressed in in vitro polarized Th1 cells, and at lower levels in Th17 cells. It is known to synergize with Toll-like receptors and is thought to regulate Th1 and Th17 cytokine secretion.