Rhesus incompatibility and aplastic anemia as the consequence of split chimerism after bone-marrow transplantation for severe combined immunodeficiency.

A patient with severe combined immunodeficiency received three transplants of bone marrow from the HLA-B- and -D-identical mother. The first transplantation led to a severe graft-versus-host reaction followed by immunological reconstitution. A split chimerism was found with engraftment only of the maternal lymphocytes. Five months after the transplantation an autoimmune hemolytic anemia was observed which was due to rhesus incompatibility as well as polyspecific antibodies. At the same time agranulocytosis developed and 9 mth after the first transplantation the child suffered from aplastic anemia. Two further attempts failed to engraft the maternal hematopoiesis. The child died during the treatment with cyclophosphamide as conditioning for a third transplantation.