Immunologic control for polyomavirus infection after kidney transplantation

Abstract

Aims: We compared the relative efficacy of urine decoy cell (UDC) and polymerase chain reaction (PCR) to identify polyomavirus (PV) infection, and investigate the efficacy of reduction of immunosuppression for earlier-stage PV infection before irreversible graft injury. Methods: A total of 222 de novo renal transplant recipients from March 2003 to September 2005 were enrolled. Prospective UDC monitoring with supplementary PV-PCR was performed. Early reduction of immunosuppression was guided by the results of UDC and PV-PCR. Results: The positive predictive value of urine cytology for PV infection was 48.8%, and the negative predictive value was 74.1%. After reduction of immunosuppression, negative conversion or significant decrease of viral titer was achieved 100% in 15 PV-PCR positive recipients. Only 3 patients who were neglected or overlooked for PV screening or positive test results early after transplantation were diagnosed as having PV nephropathy, and resulted in graft dysfunction and failure. From January 2001 to December 2002, when we did not monitor the PV infection, there were 7 cases of PV nephropathy among 116 recipients. Conclusion: The combination of UDC and PV-PCR should be considered for screening of PV infection. Reduction of immunosuppression based on UDC monitoring and PV viral loads may reduce the incidence of PV nephropathy.