High B-cell activating factor levels in multi-transfused thalassemia patients

Objectives To assess the associations between B-cell activating factor (BAFF) and alloimmunisation in multi-transfused thalassemia. Background Red blood cell (RBC) alloimmunisation is a complication of multi-transfused thalassemia. BAFF is promoting B cells that produce alloantibodies. Methods/Materials Multi-transfused thalassemia, 15 years or older, were recruited in the cohort study. Alloantibodies and BAFF levels were analysed. Results Of 114 patients, the overall prevalence of RBC alloimmunisation was 29.8%. The most common alloantibodies were anti-E, anti-Mi(a) and anti-c. BAFF levels were different among the three groups; the patients with baseline alloantibodies (median +/- interquartile range 1251 +/- 474 pg/ml), without alloantibodies (1098 +/- 453) and healthy controls (719 +/- 306), p < 0.001. The BAFF level was elevated in the >25 years old patients (vs. the <25, p = 0.011) and the buffy-coat-reduced blood recipients (vs. the pre-storage leukocyte-depletion, p = 0.005). Absolute lymphocyte count was higher in the patients without baseline alloantibodies (vs. with baseline alloantibodies, p = 0.049) and the splenectomised patients (vs. the non-splenectomised patients, p < 0.001). Of the 72 patients without baseline antibodies, four who developed new antibodies showed no statistically different BAFF levels compared with those without new antibodies after 40-month follow-up (1296 +/- 734 vs. 1062 +/- 460, p = 0.491). In multivariate analysis, BAFF to absolute lymphocyte ratio was independently associated with RBC alloimmunisation (odds ratio 3.07, 95% confidence interval 1.124-8.369, p = 0.029). Conclusion B-cell activating factor (BAFF) levels were elevated in multi-transfused thalassemia and the BAFF to absolute lymphocyte ratio was associated with red blood cell (RBC) alloimmunisation.