MONITORING AND DIAGNOSIS OF CYTOMEGALOVIRUS-INFECTION IN RENAL-TRANSPLANTATION

In this study, the utility of the cytomegalovirus antigen (CMV-AG) and the shell vial (SV) tests in the diagnosis and monitoring of posttran splant CMV infection were compared. Previous retrospective studies fro m the authors' center suggested that the CMV-AG test, which uses monoc lonal antibodies to detect viral antigen in circulating peripheral blo od leukocytes (PBL) may be both a more sensitive and specific test. A cohort of 32 renal transplant recipients was followed-up prospectively with serial CMV-AG testing, as well as conventional culture and SV fo r blood and urine and tests for immunoglobulin M (IgM) antibody. It wa s discovered that the CMV-AG test was not only more sensitive than the SV test in detecting CMV infection, but that the degree of antigenemi a as expressed by the number of positive cells per 50,000 PBL correlat ed with the likelihood and degree of symptomatic infection. All patien ts with a count > 10 positive cells/50,000 PBL developed clinical symp toms; therefore, this threshold could be useful in deciding clinically whether fever is related to CMV infection. Alternatively, if antigene mia were monitored serially after transplant, the same threshold could be used as a trigger for instituting antiviral therapy, because it wa s often reached prior to the onset of symptoms and had a high specific ity for subsequent symptomatic infection. Such an approach could obvia te unnecessary treatment of patients not destined to became symptomati c, Based upon the findings in this study, the CMV-AG test is superior to the SV assay because the actual count helps determine the likelihoo d that symptoms are a result of the virus and the processing time is s horter, it can be used to monitor the response to therapy and as a gui de to the institution of preemptive therapy.