Hematopoietic donor chimerism and graft-versus-myeloma effect in relapse of multiple myeloma after allogeneic bone marrow transplantation

A large group of patients relapsing after allogeneic bone marrow transplant ation (BMT) have obtained remission after infusion of leukocytes from their original donor, suggesting a graft-versus-myeloma effect. However, side ef fects such as graft-versus-host disease and myelosuppression are severe, an d sometimes fatal, complications of this therapeutic approach. Previously w e demonstrated that patients with leukemia who lack donor hematopoiesis in relapse after BMT experience severe and lasting aplasia after infusion of d onor leukocytes. In two patients - one with extramedullary and one with mar row relapse after a sex-mismatched transplantation - we analyzed hematopoie tic chimerism by cell sorting and bone marrow cultures. CD34-positive cells , CD4-CD8-positive cells, committed progenitors, and LTC-IC were of donor o rigin, as demonstrated by two-color fluorescence in situ hybridization (FIS H). Additionally, in relapse complete donor T-cell chimerism was seen. In c ontrast, plasma cells were of recipient origin in the patient who had a rel apse in the bone marrow. Both patients were treated with infusions of donor leukocytes from their original donor. Neither patient suffered myelosuppre ssion, and one achieved a stable complete remission.