FIG. 1.

Bacterial burden and CD4⁺ and CD8⁺ T-cell decline. (A) Numbers of bacteria in the lungs (▪), spleens (⧫), and livers (•) of mice at different times after intranasal infection with 1 × 10⁵ CFU of M. avium per mouse. The means and standard deviations based on the data for five mice per group are shown. (B and C) Changes in the percentages (B) and numbers (C) of CD4⁺ and CD8⁺ T cells in the spleens of mice at different times after infection, assayed on the same day. The values are means and standard deviations based on the data for three mice per group. The results of one representative experiment of 10 similar experiments are shown. Symbols: ▪, CD4⁺, infected; □, CD4⁺, old uninfected; •, CD8⁺, infected; ○, CD8⁺, old uninfected.