Outcomes of patients with rejection post-polyomavirus nephropathy

Introduction. We sought to determine the effects of rejection in renal transplant recipients with polyomavirus nephropathy (PVN). Methods. SCr, biopsy findings, BKV serum and urine loads (Taqman PCR), and BKV antibody titers (HA inhibition assay) were analyzed by two-sample median tests and z tests in 11 patients with median follow-up of 7.3 (2.0 to 31.5) months post-PVN. All patients underwent immunosuppression reduction (ISR) as PVN treatment. Results. Post-PVN, 3 (27%) patients had five rejection episodes, with 80% being mild. Median time to rejection was 18 (2 to 60) weeks. One hundred percent of patients who experienced post-PVN rejection also experienced rejection pre-PVN. Rejection episode treatments consisted of: none in one, increased tacrolimus in two, IVIG in one, IVIG and increased tacrolimus in one. Median viral loads in patients with post-PVN rejection versus those without rejection were not different in serum (2.01 × 10⁴ vs 9.00 × 10⁴ BKV copies/mL; P =. 22) or urine (5.37 × 10⁵ vs 8.93 × 10⁶ BKV copies/mL; P =. 28). Median BKV antibody titers were slightly lower (16384 vs 32768 HA units; P =. 02) and median SCr values were significantly higher (2.7 vs 1.9 mg/dL, P =. 0003) in patients who had experienced post-PVN rejection. Graft losses occurred in one rejection-free patient (chronic allograft nephropathy) and in one patient who experienced multiple acute rejection episodes, humoral rejection, and worsening PVN. Conclusions. Patients who experience rejection prior to PVN are at high risk of developing rejection post-ISR and post-PVN; however, low graft loss rates may still be achieved.