Antirejection treatment in kidney transplant patients with BK viruria

Background.: Kidney transplant recipients with BK virus nephropathy or viremia are generally treated with reduction of immunosuppression to facilitate virus eradication. Methods.: Prompted by biopsy findings interpreted as acute rejection, we administered intravenous bolus steroids to five patients with BK virus in the plasma (BKP) (group 1) and also tried other antirejection therapies in 13 patients with BK virus in the urine (BKU) but no BKP (group 2). Results.: All group 1 patients had continued viremia, whereas two viruric patients in group 2 developed viremia after therapy. Ultimately, after reduced immunosuppression both groups cleared BKP over 53±29 days and 50±6 days. BKU clearance was not consistently observed. One year postbiopsy, there were no graft failures (0%) in group 1 and 2 (15%) in group 2; however, suboptimal renal function was observed in 40% and 62%, respectively (P=0.6). Conclusion.: Cautious antirejection treatment to patients with active BKP or BKU can lead to two possible outcomes: (a) reduction in serum creatinine that is seemingly consistent with a diagnosis of acute rejection and (b) lack of clinical response, which in the absence of overt BK nephropathy, makes it difficult to distinguish between refractory rejection and virus-induced tissue inflammation.