[pp65 antigenemia in evaluation of cytomegalovirus infection after kidney transplantation].

INTRODUCTION

Cytomegalovirus (CMV) infection is the most common infectious complication after organ transplantation. Serology is useful only for detecting previous CMV infection. Dissatisfied with serologic follow-up after kidney transplantation, three years ago we introduced detection of CMV antigenemia by an immunocytochemical method using a monoclonal antibody specific for the pp65 CMV matrix protein. This test allows for quantification of positive leukocytes. The purpose of this paper is to present our three-year experience.

PATIENTS AND METHODS

From May 1999 till May 2002 CMV antigenemia was examined in 76 patients: 55 patients submitted to kidney transplantation during the study period, and 21 patients previously. Antigenemia became positive at 25.68 +/- 15.51 days after transplantation. These 76 patients were divided into three groups according to the number of positive cells per 200,000 leukocytes: < 5 (group I), 6-20 (group II) and > 20 (group III). The groups consisted of 23, 20 and 11 patients, respectively. The percentage of patients treated by ganciclovir was 4.34%, 15% and 100%, respectively. In group I only one patient received ganciclovir because of geographic indication, in group II three patients because of septicemia, thrombopenia and leukopenia and previous miliary tuberculosis.

RESULTS

One patient from group III with steroid diabetes died from pneumonia with abscess formation three days from admission. In another two patients, interstitial pneumonia and abscess of the arm developed. Five patients had an acute rejection episode each and were treated by high doses of methylprednisolone. Five patients had elevated temperature, transaminases were elevated in five patients, and neutropenia with or without thrombopenia was found in six patients. One patient had recurrent CMV disease and lymphocele. Two patients had preemptive treatment by ganciclovir based on positive CMV antigenemia.

DISCUSSION

Various centers differ according to the approach to treatment of CMV infection, ranging from prophylaxis to deferred treatment for CMV disease. Determination of pp65 CMV antigenemia allowed us a safe follow-up of patients after kidney transplantation. Compared with previous serologic follow-up antigenemia is a considerable progress. We did not use CMV prophylaxis because it is more expensive and can cause resistance to ganciclovir. A promising novel drug valganciclovir will allow for good prophylaxis owing to its better absorption from the gut. Based on our three-year experience, optimal cut-off for antigenemia has been set at 20 positive cells per 200,000 leukocytes. The existence of symptoms or changes in the level of leukocytes, platelets or transaminases goes in favor of treatment decision.

CONCLUSION

Cytomegalovirus pp65 antigenemia is a reliable tool in the follow-up of patients after kidney transplantation. Patients with primary CMV infection, those with rejection episode and threshold of 20 positive cells require preemptive treatment with ganciclovir. The measurement of pp65 CMV antigenemia has clinical, analytical and cost-effective advantages. Intensive monitoring for CMV infection allows for quick and specific detection of active CMV infection. This approach avoids resistance to ganciclovir. The method is simple and specific without expensive equipment. Avoidance of unnecessary prophylaxis adds to its cost-effectiveness.