FIG. 2.

Infection with M. ulcerans induces an early increase in the DLN CD4⁺ population, followed by a sharp decrease in the case of the highly virulent strain. Mice were subcutaneously infected in the footpad with 3 × 10⁵ AFB of M. ulcerans 5114 (○) or 98-912 (•). At different time points postinfection, the total number of leukocytes in the DLN of the infected footpad was determined (A), and the frequencies of CD3⁺ (B), CD19⁺ (C), CD4⁺ (D), and CD8⁺ (E) cells were determined by flow cytometry. The data points represent the means ± the SEM (n = 5) of four independent experiments. The statistical significance was calculated using the Student t test, comparing each time point with noninfected mice (*, P < 0.05; **, P < 0.01; ***, P < 0.001).