Prevalence, risk factors, and clinical impact of posttransplant anti-HLA antibodies after HLA-mismatched allografting: A multicenter prospective study

In this prospective multicenter clinical study investigated the prevalence of, and risk factors for, posttransplant anti-human leukocyte antigen (HLA) antibodies after HLA-mismatched allogeneic stem cell transplantation (allo-SCT) and their association with clinical outcomes. A total of 314 patients were enrolled. The prevalence of class I or II anti-HLA antibodies was 66.6%, 74.2%, 58% and 52.9% at days + 7, +14, + 21, and + 28 post-SCT, respectively. A significant increase in anti-HLA class I and II antibody MFI levels was observed at all four posttransplant timepoints compared with pretransplant baselines (all P  < 0.05). On the basis of the posttransplant anti-HLA antibody profile, patients were classified as follows: Cohort A (persistently positive, n = 109), Cohort B (intermittently positive, n = 166), or Cohort C (persistently negative, n = 39). Positivity for pretransplant anti-HLA antibodies could predict positivity for posttransplant anti-HLA antibodies (HR, 2.488; P  = 0.006). Persistent positivity for post-SCT anti-HLA antibodies was associated with prolonged thrombocytopenia (PT), which resulted in higher nonrelapse mortality (HR, 5.004; P  < 0.001) and lower overall survival (HR, 4.552; P  < 0.001). Our results suggest that positivity for pre-SCT anti-HLA antibodies is a risk factor for the prevalence of post-SCT anti-HLA antibodies in HLA-mismatched recipients. Persistent positivity for posttransplant anti-HLA antibodies may contribute to PT, leading to poor survival.