T-cell Depletion of Bone Marrow Does Not Inhibit in Vitro Hematopoiesis

One approach to overcome the problem of histoincompatibility in bone marrow transplantation is to use T cell depleted marrow from a haploidentical donor in an attempt to ameliorate graft-versus-host disease. Since the T cell requirements for normal hematopoiesis are uncertain, experiments were performed to study the effects of E rosette-T cell depletion on in vitro growth of hematopoietic progenitor cells. Marrow mononuclear cells were cultured in a modified CFU-GEMM assay before and after T cell depletion. The number of 7 day granulocytic and erythrocytic colonies, and 14 day granulocytic, erythrocytic and mixed colonies were enumerated and expressed in terms of colonies per 10(5) non T cells plated. T cell depletion did not result in decreased proliferation of any of these progenitors save possibly for 14 day granulocytic colonies in one of four experiments. In two cases, T cell depletion resulted in increased growth of progenitor cells. Three of four patients transplanted with T cell depleted haploidentical marrow cells engrafted. It is concluded that E rosette depletion of T cells from marrow does not decrease the potential of these cells to establish hematopoiesis in vitro or in vivo.