QUANTITATIVE ASSAY OF PP65 INTRALEUKOCYTE CYTOMEGALOVIRUS ANTIGEN IN RENAL-TRANSPLANTATION

Objective: To assess the clinical value of quantitative assay of leuko cyte cytomegalovirus antigen (LCA) in the management of immunodepresse d patients. Methods: Thirty-three kidney transplant recipients followe d a weekly follow-up protocol during the first 3 months after transpla ntation. LCA was compared with cytomegalovirus (CMV) detection in bloo d using fibroblast cell culture and with serology tests. LCA was expre ssed in number of positive cells per 2.10(5) leukocytes, detected by i mmunofluorescence with a specific monoclonal antibody directed against the pp65 antigen, The standard culture method and a rapid centrifuge method were used for blood samples. The serum level of anti CMV antibo dies was determined by ELISA. Results: CMV infection defined as positi ve viraemia and/or positive serology tests was diagnosed in 22 of the 33 patients. LCA was detected in 20 patients, including all those with clinical signs of infection. Serology was the only method giving a po sitive diagnosis in 2 patients and was negative in 3 infections positi ve for LCA. Viraemia was negative in 2 patients positive for LCA. LCA was detected in 60 of the 65 blood samples with a positive viraemia te st and in 46 of the 165 negative samples (sensitivity 92% and specific ity 72%). Quantitatively, LCA in samples taken from patients with clin ical signs was higher than that in samples taken from asymptomatic pat ients (51 +/- 5 versus 20 +/- 2, p < 0.001). In addition, LCA was dete cted a mean 7.6 +/- 4 days before significant changes in serology test s, 2.2 +/- 1.6 days before the viraemia and 7.1 +/- 1 days before clin ical manifestations. Conclusion: Leukocyte cytomegalovirus antigen giv es a sensitive means of early positive diagnosis. The quantified level illustrates the patient's risk of infection. This new method is a ver y helpful tool in following renal transplantation recipients.