Residual lymphocytes after specific depletion. Functional study

: We previously demonstrated that, following a 2-day stimulation of T cells by MHC incompatible cells, a ricin A-chain conjugated to a monoclonal anti-IL2 receptor p55 subunit can kill 1.5 log of the activated alloreactive T cells while non specific killing of alloreactive T cells of a third partner does not exceed 0.5 log. This methodology is of potential use for selective alloreactive T cell depletion in MHC incompatible bone marrow transplantation in order to prevent both graft versus host disease and graft rejection. This study shows that this T cell depletion method does not alter T cell reactivity to microorganism antigens encountered in infection following BMT. It was found that T cell proliferation to cytomegalovirus and to candida antigens is not affected as shown in proliferative assays and by limiting dilution analysis for the latter antigen.