Experience with incompatible maternal donors for bone marrow transplantation.

Marrow transplantation in aplastic anemia and leukemia has generally been limited to siblings who have been histocompatible at both the serological (A and B) and lymphocyte determined (D or MLC) loci of the HLA system. We studied three male patients, two with aplastic anemia and one with acute myelogenous leukemia, who received transplants from their histoincompatible mothers. MLC studies between donors and recipients showed varying degrees of stimulation. Definite engraftment occurred in one patient and transient engraftment in another. Engraftment in the third patient could not be evaluated. In the patient with sustained engraftment, there was clinical evidence of severe graft versus host disease (GVHD) however, this was not substantiated by histologic findings. This preliminary study suggests that MLC incompatibility may be more of an indicator of the risk of GVHD than of bone marrow rejection. If more effective control of GVHD can be accomplished, marrow transplantation between MLC-reactive individuals may become feasible.