FIG. 1.
Changes in cell number and T-cell composition in the lungs of mice following M. tuberculosis infection. C57BL/6 mice were infected intravenously with 2 × 105 viable M. tuberculosis bacilli (Erdman strain), and their lungs were harvested 0, 1, 2, 3, and 4 weeks postinfection. (A) Numbers of viable cells in lungs were counted by trypan blue exclusion. Each time point represents 4 to 10 mice. For each time point, P < 0.05 compared to uninfected mice. (B) Cells harvested from lungs were stained for CD4 (open squares) and CD8 (solid circles). The cells were gated on lymphocyte population by size and analyzed by flow cytometry. Each time point represents 4 to 10 mice; P < 0.05 for the 2-, 3-, and 4-week time points compared to day 0. Error bars show standard error. (C) Lung cells were harvested at 21 days postinfection, stained for CD4, CD8, and TCRαβ, fixed in paraformaldehyde, and analyzed by two-color flow cytometry after gating on lymphocytes. Shown are the results from samples from a representative mouse. The experiment was repeated at least three times.