MECHANISMS OF GRAFT FAILURE AFTER HUMAN MARROW TRANSPLANTATION - A REVIEW

Graft failure (GF) following bone marrow transplantation (BMT) in man is usually attributed to allograft rejection; however, other mechanisms of GF exist. Exposure of the developing allograft to viruses, myelotoxic drugs, and damage to the host-derived marrow stroma during graft-versus-host disease (GVHD) may all cause GF. Later, in the post-transplant course, recurrence of the original disease may ultimately destroy or replace the graft. Overall allogeneic rejection remains the most important cause of GF and most in vivo and in vitro evidence points to a T cell mechanism. The incidence of rejection after clinical BMT is very variable and highly dependent on HLA and non HLA histocompatibility differences between donor and recipient, the level of recipient sensitisation pre-BMT and the immunosuppressive protocols used pre-transplant and for the prevention of GVHD.