[Quantitative detection of pp65 intraleukocyte cytomegalic antigen in renal transplantation].

OBJECTIVE

To assess the clinical value of quantitative assay of leukocyte cytomegalovirus antigen (LCA) in the management of immunodepressed patients.

METHODS

Thirty-three kidney transplant recipients followed a weekly follow-up protocol during the first 3 months after transplantation. LCA was compared with cytomegalovirus (CMV) detection in blood using fibroblast cell culture and with serology tests. LCA was expressed in number of positive cells per 2.10(5) leukocytes, detected by immunofluorescence 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 antibodies was determined by ELISA.

RESULTS

CMV infection defined as positive 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 positive diagnosis in 2 patients and was negative in 3 infections positive 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 test and in 46 of the 165 negative samples (sensitivity 92% and specificity 72%). Quantitatively, LCA in samples taken from patients with clinical signs was higher than that in samples taken from asymptomatic patients (51 +/- 5 versus 20 +/- 2, p < 0.001). In addition, LCA was detected a mean 7.6 +/- 4 days before significant changes in serology tests, 2.2 +/- 1.6 days before the viraemia and 7.1 +/- 1 days before clinical manifestations.

CONCLUSION

Leukocyte cytomegalovirus antigen gives a sensitive means of early positive diagnosis. The quantified level illustrates the patient's risk of infection. This new method is a very helpful tool in following renal transplantation recipients.