Prevention of graft-versus-host disease in HLA-matched bone marrow transplantation for malignant diseases: a multicentric study of 62 patients using 3-pan-T monoclonal antibodies and rabbit complement.

Abstract

In order to evaluate the effectiveness and reproducibility of T cell depletion in human leukocyte antigen (HLA)-matched bone marrow graft to prevent graft-v-host disease (GVHD), our multicentric study (nine different centers) investigated 62 consecutive patients with poor prognosis leukemia or hematosarcoma from June 1984 to November 1985. The data were updated October 1, 1986, and the mean follow-up was 18 +/- 4.3 months. T cells were depleted with a combination of 3-pan-T cell monoclonal antibodies (CD2 "D66"; CD5 "A50"; CD7 "I21") with a single incubation of rabbit complement (C'). The average number of T cells infused was 0.66 X 10(6) +/- 0.56/kg body weight. Twenty-six patients received chemoprophylaxis for GVHD, 16 received methotrexate, and ten received cyclosporin A. Only a single case of severe (greater than grade II) GVHD was observed, yet the incidence of graft failure was 19%. Factors that might have influenced the occurrence of graft failure appear to be the lack of radiotherapy in the conditioning regimen; the conditioning regimen itself (fractionated total body irradiation [TBI], 12 Gy, v single dose is better than TBI, 10 Gy, but still not statistically significant); and the age of the patients (high-risk after 30 years of age). In contrast, neither the number of nucleated cells reinfused nor the level of T cell depletion (provided the T cells were below critical numbers) seemed to have an influence, nor did chemoprophylaxis for GVHD or splenectomy in chronic granulocytic leukemia (CGL) patients. The survival of graft failure patients was very poor (one of 11; survival at 15 months of the initial graft). Thus, our study demonstrates the reproducibility and high effectiveness in preventing GVHD by immunodepletion of T cells in a large-scale multicentric assay, in which compliance with the protocol of immunodepletion was reasonably good. This study thus provides interesting clues to overcoming graft rejection.