After major ABO-mismatched allogeneic hematopoietic progenitor cell transplantation, erythroid engraftment occurs later in patients with donor blood group A than donor blood group B

BACKGROUND: Isohemagglutinins directed against the donor blood group frequently delay erythroid engraftment after major ABO-mismatched allogeneic hematopoietic progenitor cell transplantation (HPCT). Graft-versus-host reactions are capable of accelerating the clearance of isohemagglutinins. Whether immunogenicity of the A- and B-antigen is important in this process is unknown. PATIENTS AND METHODS: Data of 807 patients from three centers were screened for patients with major or bidirectionally ABO-mismatched donors. Clinical data and red blood cell (RBC) transfusion support were analyzed retrospectively. RESULTS: A total of 158 patients with major or bidirectionally mismatched donors were identified. After major mismatched HPCT, patients with anti-A directed against the donor blood group required RBC transfusion support for a median of 109 days (range, 0-324 days) compared to 21 days (range, 2-98 days) for patients with anti-B directed against donor blood group (log-rank test, p = 0.0001). Other risk factors associated with prolonged RBC transfusion support in univariate analysis were age (p = 0.024), cytomegalovirus infection (p = 0.016), hemolytic anemia (p = 0.027), and chronic bleeding disorders (p = 0.038). The independent influence of donor blood group and recipient age were confirmed in a multivariate analysis. CONCLUSION: These results indicate that the immunogenicity of the ABO antigen plays an important role for the kinetics of erythroid engraftment after ABO-mismatched HPCT.