Onset and progression of de novo donor-specific anti-human leukocyte antigen antibodies after BK polyomavirus and preemptive immunosuppression reduction

Background BK polyomavirus (BKPyV) viremia/nephropathy and reduction in immunosuppression following viremia may increase the risk of alloimmune activation and allograft rejection. This study investigates the impact of BKPyV viremia on de novo donor anti‐human leukocyte antigen (HLA)‐specific antibodies (dnDSA). Patients and methods All primary renal transplants at East Carolina University from March 1999 to December 2010, with at least 1 post‐transplant BKPyV viral load testing, were analyzed. Patients were negative for anti‐HLA antibodies to donor antigens (tested via single antigen beads) at transplantation and at first BKPyV testing. Results Nineteen of 174 patients (11%) tested positive for BKPyV viremia. Within 24 months of BKPyV viremia detection, 79% of BKPyV‐viremic patients developed dnDSA. Only 20% of BKPyV viremia‐persistent cases, compared to 86% of BKPyV viremia‐resolved cases, developed dnDSA (P = 0.03). Poor allograft survival was evident in BKPyV viremia‐persistent patients (60% failure by 2 years post BKPyV diagnosis) and in BKPyV viremia‐resolved patients with dnDSA (5‐year post BKPyV diagnosis allograft survival of 48%). Conclusions Post‐transplant BKPyV viremia and preemptive immunosuppression reduction is associated with high rates of dnDSA. When preemptively treating BKPyV viremia, dnDSA should be monitored to prevent allograft consequences.