Cytomegalovirus antigenemia.

The cytomegalovirus (CMV) antigenemia test is a new direct method of diagnosing active CMV infection. The test is based on immunocytochemical detection of CMV immediate early antigens in blood leukocytes. Technical aspects and pitfalls are discussed. The diagnostic merits of the test are compared with those of other methods, such as isolation of virus from blood, serologic determinations, and the polymerase chain reaction. Overall, active CMV infection can be diagnosed by the detection of CMV antigenemia with a sensitivity and specificity of greater than or equal to 90%, whereas sensitivity is 100% in symptomatic patients. On average, the test provides diagnostic information at least 1 week earlier than other established methods. Moreover, the level of CMV antigenemia appears to be related to the severity of disease and to be inversely related to the level of host immunocompetence. It is concluded that (1) the test is useful for the early and rapid diagnosis of life-threatening CMV infection in immunodeficient patients, (2) the test could be a useful tool in the study of the immunopathophysiology of CMV disease, and (3) the antigenemia test may be a promising marker for monitoring disease activity and its response to specific chemotherapy.