Rapid detection of cytomegalovirus antigen on alveolar cells in bronchoalveolar fluid from transplant patients with cytomegalovirus pneumonia.

Cytomegalovirus-specific mouse monoclonal antibodies and immunomagnetic beads conjugated with sheep anti-mouse immunoglobulin G were used to screen for cytomegalovirus (CMV) antigen expressed on the surface of alveolar cells in bronchoalveolar lavage (BAL) fluid from 23 transplant recipients with interstitial pneumonia. The beads formed rosettes around the cells when CMV antigen was present on the cell surface. Results could be evaluated by light microscopy within 2 hours of receiving the specimen. Cells in BAL fluid obtained from 15 immunocompetent individuals served as controls. Cytomegalovirus antigen was expressed on the surface of the alveolar cells from 12 transplant recipients and detected by this method as rosette formation on 1-8% of the cells. CMV was isolated from culture of cells in BAL fluid and blood from all these patients except 1, while intracellular CMV antigen was detected by monoclonal antibodies and immunofluorescence in 3 only. Serological changes, indicating an active CMV infection, were present in 11/12 patients. One patient with a CMV pneumonia, later confirmed by autopsy, failed to respond with any antibody titer. No rosette formation occurred on alveolar cells from any of the 15 immunocompetent controls. Thus, the method studied appears to be a valuable complement to other diagnostic methods for CMV pneumonia in transplant recipients. When correlated with the isolation of CMV from culture, the sensitivity was 100% and specificity 92%.