Allogeneic bone marrow transplantation in adult leukaemia : Results of T-cell depletion by soybean lectin fractionation

Abstract

The aim of allogeneic bone marrow transplantation in leukaemia is ultimately to achieve a cure by elimination of residual disease. However, as a prerequisite, the patient must first survive the procedure. This requires successful engraftment and the avoidance of severe graft versus host disease (GVHD). One approach is to remove T lymphocytes from the donor marrow and there is increasing evidence to suggest that effective T cell removal significantly reduces the incidence of GVHD. Most workers employ anti-T cell monoclonal antibodies and complement mediated lysis1,2, but this has been associated with instances of unexpected graft failure. Physical methods of T cell removal have previously been mainly confined to use in children as they are labour intensive and time consuming when applied to large marrow volumes. The technique of marrow fractionation with the plant lectin soybean agglutinin (SBA) followed by sheep red blood cell (SRBC) rosetting has been used to efficiently remove T cells and allow parent-to-child, haplotype identical, transplants without GVHD3. However, despite promising preliminary data4, doubt remained that the very small cell numbers left after fractionation might prove insufficient to provide reliable engraftment in adult transplants. The aim of this study was to help resolve this question.