Tim-3 is a transmembrane protein also known as T cell immunoglobulin and mucin domain containing protein-3. Tim-3 is expressed at high levels on Th1 lymphocytes and CD11b+ macrophages. Tim-3 has also been shown to exist as a soluble protein. Cells expressing Tim-3 are present at high levels in the CNS of animals at the onset of experimental autoimmune encephalomyelitis (EAE), a disease mediated by lymphocytes secreting Th1-like cytokines. Tim-3 has been proposed to inhibit Th1-mediated immune responses and promote immunological tolerance.