Fig. 1.—
Haematoxylin-eosin staining of a Chlamydia pneumoniae-infected lung 3 days after infection (a) shows an interstitial infiltrate consisting predominantly of granulocytes. After 3 days, inflammatory infiltrates within the interstitium, the bronchiolar and alveolar space decreased and became dominated by mononuclear cells (b, 7 days post-infection). C. pneumoniae antigen was detected in both cell types by immunohistochemistry (c, granulocytes, 3 days post-infection; d, macrophages, 7 days post-infection, genus-specific antibody CF‐2), and in bronchiolar epithelium (e, 7 days post-infection) and alveolar epithelium (f, 7 days post-infection). C. pneumoniae antigen was detected in peribronchiolar lymphatic tissue 7 days post-infection (g). Infected cells were identified as macrophages by a specific antibody RAM 11 in a consecutive section (h). Chlamydial antigen was detected in the spleen (i) and in the media of the aorta, where spindle-shaped cells resembling smooth muscle cells were infected (j). Scale bar=100 µm.