Analysis of Rejection in HLA Matched T-Depleted Bone Marrow Transplants

In February 1984 a collaborative trial was begun using the Royal Free (RF) cocktail of MBG6 and RFT8 monoclonal antibodies to T-deplete donor marrow for allogeneic BMT for leukaemia. The trial followed the successful use of the cocktail in 25 patients. A proportion of patients from all centres experienced rejection of the graft. Because of this serious problem, T-depletion was temporarily suspended at the other centres. In the parent institution all but 1 of the subsequent 13 grafts were successful. Rejection occurred in 3 forms: no engraftment at all; partial or complete engraftment followed by early loss of graft, or late loss of graft (at 4 months). Preliminary data from centres using other anti-T cell monoclonal antibodies and from this study strongly implicate the pre-transplant conditioning as being critical to successful, sustained engraftment.