ANTIGENEMIA, IMMUNOBLOTTING, AND ENZYME-IMMUNOASSAY FOR EARLY DIAGNOSIS OF CYTOMEGALOVIRUS-INFECTION IN RENAL-TRANSPLANT PATIENTS

Timely and rapid diagnosis of cytomegalovirus (CMV) infection is impor tant for the management of transplant patients. We compared three sero logical assays, IgM immunoblot and IgG/IgM enzyme immunoassay (EIA), a s well as the detection of CMV antigens in polymorphonuclear blood leu kocytes (antigenemia), for their value in the early diagnosis of CMV i nfection. Thirty-one patients were monitored longitudinally for 3 mont hs after renal transplantation. Laboratory documented CMV infection oc curred in 20 patients. All of these cases showed a positive IgM immuno blot result that was confirmed by at least one of the other test assay s (IgG EIA 19/20, antigenemia assay 13/20, and IgM EIA 12/20). All of the ten patients whose clinical picture was compatible with symptomati c CMV disease were positive for CMV infection according to IgM immunob lot and IgG EIA, nine were positive according to the antigenemia assay , and seven were positive according to IgM EIA. With reference to the temporal pattern, the antigenemia assay indicated CMV infection signif icantly earlier than the serological tests (P less-than-or-equal-to 0. 05). In symptomatic patients CMV antigen-positive leukocytes were, on the average, detected on the day of onset of symptoms, whereas detecti on by IgM immunoblot, IgG EIA, and IgM EIA followed 8, 13, and 14 days later, respectively. These results show that: (1) the CMV antigenemia assay is very useful for the early diagnosis of symptomatic CMV infec tions; (2) CMV antibodies, as an indicator of CMV infection, are detec table earlier and more frequently by IgM immunoblot than by IgG/IgM EI A; (3) compared to CMV antigenemia, the IgM immunoblot indicated CMV i nfection more often but significantly later; and (4) only a combinatio n of several diagnostic methods allows optimal detection of CMV infect ions in renal transplant patients.