Evaluation of human cytomegalovirus latency in alveolar macrophages

Cytomegalovirus (CMV) pneumonia is a major cause of illness in immunocompromised patients. The sites of human CMV (HCMV) latency are still not clearly defined. The present study was therefore designed to investigate the hypothesis that alveolar macrophages could constitute such a site. DNA extracted from alveolar cells collected by bronchoalveolar lavage and blood mononuclear cells (BMC) from asymptomatic nonimmunocompromised CMV-seropositive and CMV-seronegative patients were investigated. Controls consisted of DNA from a CMV-infected MRC5 cell line, BMC and alveolar macrophages from patients with acute CMV infection. Polymerase chain reaction (PCR) was designed for detection of a 290-bp fragment of the promoter region of the major immediate early gene of HCMV conserved within the various HCMV strains and without homology with the human genome. The limit of detection of the method was evaluated to be one HCMV viral copy per 10(4) cells. HCMV DNA was detected in BMC or alveolar cells of all patients with acute CMV infection. In contrast, no HCMV DNA was detected in alveolar cells and BMC from nonimmunocompromised asymptomatic HCMV-seropositive patients. In conclusion, in the present experiment, no latent HCMV could be detected in alveolar cells collected in nonimmunocompromised asymptomatic CMV-seropositive patients.