[Influences of an anti-pan-T cell ricin A-chain immunotoxin on generation of human immunocompetent T cells and hematopoietic progenitor cells].

SOKT1 -RTA immunotoxin, which consisted of an anti-pan-T cell monoclonal antibody SOKT1 and ricin toxin A-chain, decreased the peripheral blood lymphocyte transformation in response to PHA and to alloantigen by 92.9% and 84.7%, respectively. The generation of allocytotoxic T cell was also dramatically inhibited by this immunotoxin. After treatment of human bone marrow mononuclear cells with the immunotoxin, erythroid proliferation in CFU-E test preserved 62.9%. Based on these findings, we concluded that SOKT1-RTA immunotoxin can effectively inactivate human T lymphocytes in vitro without serious toxic effect on the hematopoietic progenitor cells. It may be an effective agent in aGVHD prophylaxis.