In situ characterization of human cytomegalovirus infection of bronchiolarcells in human transplanted lung

Distal airway cell infection by human cytomegalovirus (HCMV) in transplante d lung has been occasionally reported but not systematically investigated. The present study aimed at testing the prevalence of HCMV bronchiolar infec tion in human transplanted lung. We identified and immunophenotyped, with d ouble labeling, infected lung cells in 31 transbronchial biopsies with HCMV infection, containing distal airways (7 HCMV pneumonias, 7 HCMV infection without inflammation, and 17 morphologically occult, non-cytopathic HCMV in fection). HCMV-infected cells in pneumonias, localizations. and occult infe ctions were alveolar epithelia (32.8%. 42.8%, and 53.5%. respectively), end othelia (22.9%. 24.7%, and 26.4%. respectively), macrophages (0.006%, none, and none, respectively), airway epithelia (0.01%. 8.9%, and none, respecti vely), and bronchiolar smooth muscle cells (0.011%, 14.6%, and 16.1%, respe ctively). Ciliated and bronchiolar smooth muscle cells in transplanted lung only occasionally harbored viral infection and never showed viral cytopath y. On the basis of our morphological observations, HCMV infection of bronch iolar wall cells is rare. while alveolar epithelia and capillary endothelia l cells are the major targets of lung infection.