HLA-Mismatched Renal Transplantation without Maintenance Immunosuppression

Abstract

for the Immune Tolerance Network TO THE EDITOR: We previously reported results of our study of combined kidney and bone marrow transplantation without maintenance immunosuppression. We extended the study to include five additional patients. Here we report longer follow-up of the initial five patients and observations made after 3 years in the later cohort (Table 1). Both trials were sponsored by the Immune Tolerance Network and are currently closed to further enrollment. The first five patients received the previously described conditioning regimen (regimen 1): cyclophosphamide, thymic irradiation, anti-CD2 monoclonal antibody, and an 8-to-14-month course of a calcineurin inhibitor.1 After irreversible acute humoral rejection was observed in Patient 3, who was retrospectively found to have preformed antidonor HLA class I antibodies, the regimen was modified to include two doses of rituximab before transplantation (regimen 2). Since low levels of donor-specific antibodies developed in Patients 4 and 5, the regimen was further modified to include two additional doses of rituximab (regimen 3). Patient 1 remained well, without rejection for more than 10 years. Patient 2 also remained