Prevalence of HLA antibodies in remotely transfused or alloexposed volunteer blood donors

Abstract

HLA antibody testing of previously transfused or pregnant donors may help reduce the risk of transfusion-related acute lung injury (TRALI). However, the prevalence of HLA antibodies in transfused donors has not been well characterized. Transfusion and pregnancy history was obtained from consenting donors. HLA Class I and II antibody testing was performed by multiantigen bead Luminex platform. Cutoff values for Class I and II antibodies used normalized background ratios of 10.8 and 6.9, respectively. Linear probability models were used to evaluate potential associations between HLA alloimmunization and donor characteristics. A total of 7920 donors (2086 males and 5834 females) were tested. HLA antibody prevalence did not significantly differ between 895 transfused (1.7%) and 1138 nontransfused males (1.0%; odds ratio [OR], 1.75; 95% confidence interval [CI], 0.80-3.82]. Prevalence in 45 transfused nulliparous females (4.4%; 95% CI, 0.1%-11.8%) was not different from the 1.6% prevalence in 1732 nontransfused nulliparous females (OR, 2.94; 95% CI, 0.68-12.74). Transfused parous females had higher prevalence than nontransfused counterparts (p = 0.004; OR, 1.39; 95% CI, 1.07-1.80). In a linear probability model, the estimated additive risk of transfusion-induced alloimmunization was only 0.8% (95% CI, -0.2% to 1.8%; p = 0.10). Donor transfusion history showed that 58% of transfusions occurred more than 10 years previously. Transfused volunteer blood donors do not appear to have a significantly higher prevalence of HLA antibodies than their nontransfused counterparts. Thus, in an effort to reduce TRALI risk, ascertaining past history of transfusion and testing these donors for HLA antibodies is not necessary.