Immune reconstitution after bone-marrow transplantation.

Recipients of both allogeneic and autologous BMT demonstrate clinically significant immune deficiency involving T and B lymphocytes. While quantitative aspects of the immune system generally return to normal in the first 3 to 4 months, there is a prolonged delay in the recovery of qualitative immune functions. T-cell proliferation is impaired immediately after transplantation and recovers after more than 1 year. There is a documented defect in IL-2 producing cells post-BMT, but PHA-stimulated T cells are TAC+. Therefore, addition of IL-2 in vitro may normalize the T-cell proliferation defect. NK and LAK activities normalize very early post-BMT. In the light of these data, the clinical assessment of rIL-2 administration on the immunological reconstitution of ABMT patients and as consolidative immunotherapy is being investigated.