Anti-VSIR antibodies are used in the immunodetection of the protein V-set immunoregulatory receptor. In humans, the canonical protein has a reported length of 311 amino acid residues and a mass of 33.9 kDa. Its subcellular localization is in the cell membrane. It is notably expressed in spleen. VSIR is reported to be an immunoregulatory receptor, which inhibits the T-cell response. Post-translational modifications have been described, including N-glycosylation and protein cleavage. VSIR is also used as a cellular marker for characterizing microglia. Synonyms for this target antigen include Death Domain1alpha, PDCD1 homolog, V-domain Ig suppressor of T cell activation, and V-type immunoglobulin domain-containing suppressor of T-cell activation. VSIR gene orthologs have been reported in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species. Over 130 citations in the literature describe the use of VSIR antibodies in research. Flow Cytometry is a widely used application for these antibodies. ELISA and Immunohistochemistry are also common applications.