B‐cell activating factor, a predictor of antibody mediated rejection in kidney transplantation recipients

Aim Donor‐specific antibody (DSA) is a widely‐used biomarker for antibody‐mediated rejection (ABMR) but correctly indicates only 30–40% of patients with ABMR. Additional biomarkers of ABMR in kidney transplant recipients are needed. Methods All 68 kidney transplanted‐recipients enrolled in this study were negative for graft rejection as determined by surveillance‐biopsy ELISA at day 7 post‐transplantation. Allograft biopsy was then performed at 6 months post‐transplantation for subclinical‐ABMR detection. Recipients were stratified by pre‐transplant DSA and BAFF at day 7 into four groups. Results During the study period, 13.2% of the recipients demonstrated subclinical‐ABMR at 6 months, without patient with clinical ABMR presentations. Overall mean BAFF at day 7 was 393 pg/mL (95% CI = 316–471 pg/mL). The optimal cut‐off value for low vs. high BAFF level was 573 pg/mL, with sensitivity and specificity at 77.8% and 88.1%, respectively. Fifty percent of recipients with high BAFF at day 7 (14 patients) and only 3.7% of patients with low BAFF demonstrated ABMR (P