OKT3 incubation of donor marrow for prophylaxis of acute graft-vs.-host disease (GvHD) in allogeneic bone marrow transplantation.

Following allogeneic (matched or minor mismatched) bone marrow transplantation with marrow incubated with OKT3, 17 patients have been observed for at least 60 days for the development of acute graft-vs.-host disease. One milligram of the monoclonal (murine) antibody OKT3 was incubated with the donor marrow for one hr at room temperature prior to infusion. It was anticipated that coated/opsonized immune competent T lymphocytes would subsequently be phagocytosed by the recipient reticulo-endothelial system. Three of 17 patients developed Grade II or greater acute graft-vs.-host disease. In two, this proved fatal when complicated by cytomegalovirus infection. Eleven patients showed no evidence of acute graft-vs.-host disease and three had transient limited skin rashes (Grade I graft-vs.-host disease). Opsonization of T lymphocytes has reduced the incidence of severe acute graft-vs.-host disease in this unit from 79% (historical group) to 18% when added to prophylactic methotrexate given according to the Seattle protocol.