Detection of cytomegalovirus (CMV) antigens in kidney biopsies and transplant nephrectomies as a marker for renal graft dysfunction

Chronic rejection accounts for the greatest loss of renal allografts. HLA m ismatching has been minimised by organ allocation and new immunosuppressive drugs have been employed, but the average cadaveric graft survival still d oes not exceed 12 years. Though the aetiology is multifactorial, one contri butory factor for this condition is cytomegalovirus (CMV). Detection of CMV in kidney biopsies and sera can diagnose and monitor this inflammatory eve nt and define its role in chronic nephropathy. Twenty five biopsies taken a t the time of transplantation. 10 biopsies for graft dysfunction and tissue blocks from 20 explanted kidney grafts were collected and investigated for CMV antigens by immunohistochemistry. Tissue samples were snap frozen and cryostat sections were incubated with monoclonal antibodies for CMV antigen s followed by immunoperoxidase staining. In 12 out of 20 transplant nephrec tomies CMV antigens were found. Only two of these patients had clinical CMV disease. Time 0 biopsies from CMV seronegative donors (n = 11) and CMV ser opositive donors (n = 14) were negative for CMV antigens. The prevalence of CMV antigens in grafts lost due to chronic rejection was 60%. These antige ns were not found within the time 0 biopsies, but were detected in 30% of b iopsies taken at the time of clinical graft dysfunction. CMV appears to con tribute to chronic rejection even without clinical disease.