Mouse TIM-3 Antibody

TIM-3 (T cell immunoglobulin and mucin domain-3) is a 60 kDa member of the TIM family of immune regulating molecules. TIMs are type I transmembrane glycoproteins with one Ig-like V-type domain and a Ser/Thr-rich mucin stalk (1-3). There are three TIM genes in human and eight in mouse. Mature mouse TIM-3 consists of a 174 amino acid (aa) extracellular domain (ECD), a 21 aa transmembrane segment (TM), and a 67 aa cytoplasmic tail (4). Two alternately spliced isoforms have been reported in mouse which lack either the TM or both the TM and mucin regions (5, 6). Within the ECD, mouse TIM-3 shares 58% and 74% aa sequence identity with human and rat TIM-3, respectively. TIM-3 is specifically expressed on Th1 cells whereas TIM-1 and TIM-2 are expressed on Th2 cells. In chronic inflammation, autoimmune disorders, and some cancers, TIM-3 is upregulated on several other hematopoietic cell types and on hippocampal neurons (9-12). The glycosylated Ig domain of TIM-3 binds cell-associated galectin-9 which induces TIM-3 Tyr phosphorylation and proapoptotic signaling (10, 13). TIM-3 functions as a negative regulator of Th1 cell activity. Its blockade results in increased IFN-gamma production, Th1 cell proliferation, and cytotoxicity (5, 7, 12, 14). TIM-3 may play a role in regulatory T cell development (7), inflammation (15), and immune tolerance (5, 13, 14). Soluble mouse TIM-3 has been shown to inhibit anti-tumor effector T cell responses and to enhance autoimmune reactions (6, 7).