High-Dose Intravenous Immunoglobulin Treatment of Polyomavirus Nephropathy Developing After T Cell-Mediated Rejection...

Reactivation of BK polyomavirus causes destructive virus allograft nephropathy; however, treatment options are limited. Herein, we report a case in which a patient with T cell-mediated rejection was treated with steroid therapy. The patient subsequently developed BK viremia and was successfully treated by using intravenous immunoglobulin (IVIG) after failing to respond to conventional treatment.

A 54-year-old man had been undergoing peritoneal dialysis for 3 years before kidney transplantation. He had an elevated serum creatinine level (2.26 mg/dL; normal range, 1.2-1.4 mg/dL) and reduced urine output 2 months after transplantation. Suspecting T cell-mediated rejection, steroid pulse therapy (methylprednisolone 250 mg twice daily) was performed for 3 days. Despite treatment, there was a recurrence of increased serum creatinine, and real-time quantitative polymerase chain reaction (serum samples) indicated BK viremia (>5.5 × 10⁵ copies/mL). Results of a kidney biopsy revealed polyomavirus nephropathy (BK virus positive and C4d negative). Thus, the patient's tacrolimus dosage was reduced (from 2.75 mg twice daily to 2 mg once daily), he discontinued mycophenolate mofetil, and he was administered ciprofloxacin and leflunomide. However, the BK viremia showed no improvement, even after 3 months of treatment. Thus, he was administered high-dose IVIG (1 g/kg, 5 times over 5 weeks). The viremia load (blood specimen) decreased to 5197 copies/mL, and the patient's graft function stabilized. His serum creatinine decreased to 2.68 mg/dL. The patient is currently being followed up.

Optimal BK treatment methods have not been established, and IVIG treatment remains controversial. However, the present case provides an example of successful treatment using high-dose IVIG.