Transplantation of T-lymphocyte-depleted bone marrow between HLA-mismatched individuals.

Four patients with acute leukemia received transplants from HLA-mismatched, related donors. Marrow cells that had been depleted of T lymphocytes using a monoclonal anti-T-lymphocyte antibody and rabbit complement were used. In vitro studies showed that 80-97% of the mature T lymphocytes were removed using this procedure. Infusion of the treated marrow was accomplished without complications, and engraftment occurred in each case. Graft-versus-host disease occurred in 3 of the 4 patients. These results show that additional manipulations of the marrow will be required to allow complete T lymphocyte removal from the marrow before the feasibility of this approach in HLA-mismatched patients can be determined.

Utility of monoclonal antibodies in the immunologic phenotyping of acute lymphoblastic leukemia.

Peripheral blood and/or bone marrow lymphoblasts from 34 children and 11 adults with acute lymphoblastic leukemia (ALL) were evaluated with a monoclonal anti-Ia antibody and a monoclonal anti-pan T-cell antibody (T101) specific for a 65,000-dalton T-cell antigen (T65). Seventy-six per cent of cases were Ia+T65-, 20% were Ia-T65+ and the remaining 4% were Ia-T65-. Anti-Ia and T101 reactivity were mutually exclusive and no Ia+T65+ cases were identified. In childhood ALL, the Ia+T65- phenotype was associated with good prognostic factors and longer median disease-free survival than Ia-T65+ patients whose clinical parameters resembled those characteristic of high-risk T-cell ALL. Included in the Ia-T65+ group were three E-rosette negative cases with clinical features of T-cell disease. Our findings compare favorably with the results of other investigators utilizing polyclonal antisera and suggest that these monoclonal antibodies, which offer the advantages of monospecific standardized reagents, will prove useful in the immunologic characterization of ALL.