Matched unrelated bone marrow transplantation for combined immunodeficiency

Bone marrow transplantation (BMT) from siblings is the treatment of choice for severe combined immunodeficiency (SCID). The objective of this study was to evaluate the efficiency of BMT from matched unrelated donors (MUD) in congenital immunodeficiencies when a sibling donor is unavailable. Sixteen consecutive patients with SCID (n = 9) and CID (n= 7), were referred for an unrelated donor search. Acceptable donors were found for all patients. Fifteen patients received busulfan and cyclophosphamide pretransplant conditioning. One patient had an early loss of graft and was reconditioned using cyclophosphamide and total body irradiation. The graft-versus-host disease (GVHD) prophylaxis used was methylprednisolone, cyclosporin A with or without methotrexate. Neutrophil engraftment was rapid and was achieved in all patients within a mean of 15.4 days. Only 13 episodes of fever were recorded shortly after BMT. GVHD of grade II or more was apparent in 2/9 (22%) of SCID patients and in 4/7 (57%) of CID patients. Overall survival was 75% with a mean follow-up of 47.4 months (range 18-101). Six out of nine SCID patients (67%) and 6/7 (86%) of CID patients are alive and well. Eleven patients had normal humoral immunity, and cell-mediated immunity as measured by flow cytometry and mitogenic responses, was intact in all patients. Intradermal candida skin test was positive in 9/10 patients tested. We conclude that BMT from MUD results in rapid engraftment and is therefore associated with a low rate of infection contributing to the improved survival rate. The protocol used is especially favorable for patients with combined immunodeficiency.