TCR gamma/delta bearing lymphocytes in peripheral blood of allogenic bone marrow transplanted patients.

The presence of two distinct T-cell receptors (TCR) alpha/beta and gamma/delta dimers as well as of the activated T cells was analysed in peripheral blood mononuclear cells from seventeen recipients of allogeneic bone marrow transplants for leukemia and for severe aplastic anemia. Nine of seventeen recipients expressed an elevated percentage of T cells bearing TCR gamma/delta receptors in their peripheral blood. Seven out of nine cases having elevated gamma/delta positive cells showed chronic graft-versus-host (GVH) disease; one patient was treated with Cyclosporin A, and one patient was asymptomatic. In the twelve patients with GVH or other clinical symptoms, activated T cells (CD3+/HLA-DR+) were elevated indicating an autoreactive or alloreactive cell population. Our results confirmed earlier in vitro data showing that TCR-gamma/delta-bearing lymphocytes may be an activated T-cell population, and this T cell subset might be involved in mediating GVH disease, or in prolonging immunodeficiency after transplantation.