Fig. 4.

Neutrophil accumulation in the lungs of mice with TB. Mice were infected with M. tuberculosis Erdman or H37Rv by aerosol. At 2, 4 and 24 weeks p.i. isolated lung leukocytes were analyzed by flow cytometry. Neutrophils were defined as Ly-6G^hi CD11b^hi cells. For AFB⁺ neutrophils, lung leukocytes were harvested and cytospin slides were processed for Ziehl-Neelsen staining. AFB⁺ neutrophils were identified based on nuclear morphology and acid-fast bacilli. (A) The proportion CD45⁺ Ly-6G^hi CD11b^hi neutrophils among all CD45⁺ lung leukocytes was higher in Erdman-infected mice (light bars) at 2 and 4 weeks p.i. compared to H37Rv-infected mice (dark bars). (B) Total lung neutrophil counts and AFB⁺ neutrophil counts in mice infected with M. tuberculosis Erdman (light bars) or H37Rv (dark bars). AFB⁺ neutrophil counts in both groups (hatched bars). Total neutrophil counts in Erdman-infected and H37Rv-infected mice were not significantly different at any time point but the number of AFB⁺ neutrophils was significantly greater in Erdman-infected mice at 2 and 4 weeks p.i. P<0.001. Data are presented as the mean ± SD (n=3) * P<0.01.