Fig. 2.

Analysis of T lymphocyte populations in uninfected mice and in mice with latent Mycobacterium tuberculosis infection. Mice were infected intranasally with 10³ colony-forming units (CFU) of M. tuberculosis. Twelve weeks after the initial infection, when latent infection was established (see Fig. 1), the mice were killed and the T cell populations from these mice and from age-matched uninfected control mice were analysed by flow cytometry. The number of T cells was determined by multiplying the total number of viable cells by the percent of CD3⁺ T cells in the population isolated from the lung, spleen, and mediastinal lymph nodes. The number of CD4⁺ and CD8⁺ cells was calculated by multiplying the percentage of gated CD4⁺ or CD8⁺ cells harvested from each organ by the total number of CD3⁺ cells. Finally, dual expression of CD45RB and CD44 was calculated by multiplying the percentage of gated populations determined to be either high and low expressors of CD45RB and CD44 by the total number of either CD4⁺ or CD8⁺. (a) Lung. (b) Mediastinal lymph node. (c) Spleen. Values represent means ± s.e.m. for four groups of n = 3 mice. The effect of infection with M. tuberculosis on T cell populations in lung and mediastinal lymph node was significantly different as determined by anova. □, Uninfected; ▪, latent infection.