FIGURE 4.

Bacterial burdens, histopathology and immune response in murine airways during chronic infection by clinical nontypeable Haemophilus influenzae (NTHi) strain. Mice were infected intratracheally with NTHi-embedded agar beads. Bacterial loads in the lung (a) and the incidence of chronic infection (b) were measured at 14 days post-infection. Haematoxylin and eosin staining of lung tissue sections was performed for control mice (c), ATCC 49766 (d) and NTHi 50 (e) infected mice. Stars indicate the presence of agar beads in bronchial lumens, arrowheads indicate the presence of neutrophils and macrophages in bronchial lumens, and arrows indicate the presence of lymphocyte aggregates. Representative images are shown from the i) lower (scale bar=2 mm) to the ii) higher magnification (scale bar=200 µm). Recruitment of (f) leukocytes, (g) neutrophils, (h) monocytes/macrophages, (i) T-cells, (j) γδ T-cells and (k) CD4⁺ T-cells was measured by flow cytometric analysis in cell suspensions of murine lungs at 14 days post-infection. The data are pooled from at least two independent experiments n=7 (ATCC49766), n=9 (NTHi 50). ns: not significant; *: p<0.05 (Mann–Whitney t-test).