Treatment of donor bone marrow with OKT3 (PAN-T monoclonal antibody) for prophylaxis of graft-vs.-host disease (GvHD) in histocompatible allogeneic bone marrow transplantation (BMT): a pilot study.

Ten consecutive patients ranging in age from seven to 34 years undergoing bone marrow transplantation from histocompatible siblings for treatment of hematologic malignancy were entered into a pilot study designed to test the safety of OKT3 pretreatment of donor bone marrow for prevention of graft-vs.-host disease. Concentrated donor bone marrow specimens containing a mean of 6.5 X 10(8) nucleated cells/kg recipient weight were treated with 1 mg of OKT3 at 4 degrees C for 30 min prior to administration to the recipient. In vitro immunofluorescent studies confirmed that all OKT3+ cells in bone marrow had effectively bound antibody. Furthermore the addition of neonatal rabbit complement in vitro decreased the proliferative responses of donor bone marrow cells to phytohemagglutinin and concanavalin A (Con A) to less than or equal to 4% of untreated bone marrow. No significant complications resulted from the administration of OKT3 and all recipients engrafted after a mean duration of 22 days. Nine of the 10 patients survived for more than 100 days after marrow transplantation. However, five of the 10 patients developed acute graft-vs.-host disease and required steroid therapy. While this pilot study suggests that OKT3 can be used safely in the bone marrow transplantation setting, further modification of our OKT3 treatment procedure will be necessary to completely eradicate graft-vs.-host disease in histocompatible bone marrow transplantation.