BTI-322 is a rat monoclonal IgG2b targeting the CD2 antigen on T cells and NK cells. It effectively blocks primary and memory alloantigen proliferative responses in vitro and identifies over 90% of E-rosette-forming peripheral blood lymphocytes and T-cell leukemia. BTI-322 has immunosuppressive activity and suppresses T-cell responses to allogeneic cells in vitro, serving as a T-cell depleting agent. It is used in research on kidney transplant rejection and steroid-resistant acute graft-versus-host disease.