Will mixed chimerism cure autoimmune diseases after a nonmyeloablative stem cell transplant?

Background. Mixed chimerism after allogeneic bone marrow transplantation ha s been shown to cure a number of genetic disorders in both the clinical and experimental settings. Although encouraging results have been reported fro m animal experiments, the role of mixed chimerism. in eliminating autoimmun e disorders is not clear. Methods. A 50-year-old man with extensive psoriasis received an allogeneic transplant from his brother after nonmyeloablative conditioning with fludar abine, melphalan, and Campath-1H for relapsed non-Hodgkin's lymphoma. The c himerism status and the immunological recovery after the transplant were se rially monitored. Results. Twenty-one months after the transplant, the patient continues to b e in complete remission from psoriasis and lymphoma with stable mixed chime rism (30% to 40% donor cells), despite significant recovery of T-cell subse ts and antigen-specific response. Conclusions. If mixed chimerism can be achieved safely with novel low-inten sity conditioning regimens and results in sustained remission of autoimmune diseases, allogeneic transplantation may become a realistic therapy in the management of some patients with autoimmune disease.