In this study, we present seven patients for whom the combined therapies of PP/IVIG were successful in reversing AHR mediated by Ab specific for donor HLA antigens. Furthermore, this protocol shows promise for eliminating DSA preemptively among patients with low-titer positive antihuman globulin-enhanced, complement-dependent cytotoxicity (AHG-CDC) cross-matches, allowing the successful transplantation of these patients using a live donor without any cases of HAR.

Human narcolepsy-cataplexy, a sleep disorder associated with a centrally mediated hypocretin (orexin) deficiency, is tightly associated with HLA-DQB1*0602. Few studies have investigated the influence that additional HLA class II alleles have on susceptibility to this disease. In this work, 1,087 control subjects and 420 narcoleptic subjects with cataplexy, from three ethnic groups, were HLA typed, and the effects of HLA-DRB1, -DQA1, and -DQB1 were analyzed. As reported elsewhere, almost all narcoleptic subjects were positive for both HLA-DQA1*0102 and -DQB1*0602. A strong predisposing effect was observed in DQB1*0602 homozygotes, across all ethnic groups. Relative risks for narcolepsy were next calculated for heterozygous DQB1*0602/other HLA class II allelic combinations. Nine HLA class II alleles carried in trans with DQB1*0602 were found to influence disease predisposition. Significantly higher relative risks were observed for heterozygote combinations including DQB1*0301, DQA1*06, DRB1*04, DRB1*08, DRB1*11, and DRB1*12. Three alleles-DQB1*0601, DQB1*0501, and DQA1*01 (non-DQA1*0102)-were found to be protective. The genetic contribution of HLA-DQ to narcolepsy susceptibility was also estimated by use of lambda statistics. Results indicate that complex HLA-DR and -DQ interactions contribute to the genetic predisposition to human narcolepsy but that additional susceptibility loci are also most likely involved. Together with the recent hypocretin discoveries, these findings are consistent with an immunologically mediated destruction of hypocretin-containing cells in human narcolepsy-cataplexy.

Cyclophosphamide (Cy) is a potent immunosuppressive agent that is selectively toxic to lymphocytes proliferating in response to recent antigen stimulation. In animal models, both graft rejection and GVHD after histoincompatible BMT can be inhibited by the posttransplantation administration of high-dose Cy. Therefore, a phase I clinical trial was undertaken to determine the minimal conditioning, including posttransplantation Cy, that permits the stable engraftment of partially HLA-mismatched marrow (up to 3 HLA antigens) from first-degree relatives. Thirteen patients (median age, 53 years) with high-risk hematologic malignancies received conditioning with fludarabine, 30 mg/m2 per day from days -6 to -2, and TBI, 2 Gy on day -1. All patients received Cy, 50 mg/kg on day 3, mycophenolate mofetil from day 4 to day 35, and tacrolimus from day 4 to day > or = 50. Three patients in cohort 1 received no additional conditioning, and 2 experienced graft rejection. Ten patients in cohort 2 received identical conditioning with the addition of Cy 14.5 mg/kg on days -6 and -5. Sustained donor cell engraftment occurred in 8 of these patients, with a median time to absolute neutrophil count > 500/microL of 15 days (range, 13-16 days) and to unsupported platelet count > 20,000/microL of 14 days (range, 0-26 days). All patients with engraftment achieved > or = 95% donor chimerism within 60 days of transplantation. Two patients with myelodysplastic syndrome rejected their grafts but experienced autologous neutrophil recovery at 24 and 44 days. Histologic acute GVHD developed in 6 patients (grade II in 3 patients, grade III in 3 patients) at a median of 99 days (range, 38-143 days) after transplantation and was fatal in 1 patient. At a median follow-up of 191 days (range, 124-423 days), 6 of 10 patients in cohort 2 were alive, and 5 were in complete remission of their disease, including both patients with graft rejection. These data demonstrate that partially HLA-mismatched bone marrow can engraft rapidly and stably after nonmyeloablative conditioning that includes posttransplantation Cy. Clinically significant antitumor responses occur, even among patients who reject their donor grafts.

Although some reports have found increasing HLA disparity between donor and recipient to be associated with fewer relapses after allogeneic blood or marrow transplantation (BMT), this potential benefit has been offset by more graft-versus-host disease (GVHD) and nonrelapse mortality. However, the type of GVHD prophylaxis could influence the balance between GVHD toxicity and relapse. We analyzed the impact of greater HLA disparity on outcomes of a specific platform for nonmyeloablative, HLA-haploidentical transplantation. A retrospective analysis was performed on 185 patients with hematologic malignancies enrolled on three similar trials of nonmyeloablative, related donor, haploidentical BMT incorporating high-dose posttransplantation cyclophosphamide for GVHD prophylaxis. No significant association was found between the number of HLA mismatches (HLA-A, -B, -Cw, and -DRB1 combined) and risk of acute grade II–IV GVHD (hazard ratio .89, P = .68 for 3–4 versus fewer antigen mismatches). More mismatching also had no detrimental effect on event-free survival (on multivariate analysis, hazard ratio .60, P = .03 for 3–4 versus fewer antigen mismatches; hazard ratio .55, P = .03 for 3–4 versus fewer allele mismatches). Thus, greater HLA disparity does not appear to worsen overall outcomes after nonmyeloablative haploidentical BMT with high-dose posttransplantation cyclophosphamide.