The 30-H12 monoclonal antibody specifically binds to CD90.2 (Thy-1.2) alloantigen on thymocytes, most peripheral T lymphocytes, some intraepithelial T lymphocytes (IEL, DEC), epithelial cells, fibroblasts, neurons, hematopoietic stem cells, but not B lymphocytes, of most mouse strains. Thy-1.2 has also been initially reported to be detectable on thymic dendritic cells, but later revealed that the antigen was probably picked up from T-lineage cells. 30-H12 mAb has been reported not to cross-react with Thy-1.1 (e.g., AKR/J, PL), or with rat Thy-1. CD90 is a GPI-anchored membrane glycoprotein of the Ig superfamily which is involved in signal transduction. In addition, there is evidence that CD90 mediates adhesion of thymocytes to thymic stroma. It has been reported that crosslinked 30-H12 antibody induces Ca2+ influx into thymocytes and that co-crosslinking of 30-H12 mAb with antibody to the CD3/TCR complex intensifies thymocyte signal transduction, promotes apoptosis of thymocytes, and inhibits the CD3-mediated proliferative response of mature T lymphocytes.