The differential expansion of CD4⁺ and CD8⁺ T cells by high and low dose infections, respectively is sustained during recall response.

<p>C57BL/6 mice infected with low dose (1×10³) and high dose (2×10⁶) <i>L. major</i> and allowed to completely resolve (heal) their lesion (>12 wks.). Healed mice were sacrificed and dLN cells were labelled with CFSE dye and co-cultured with <i>L. major</i>-infected BMDCs at a DC:dLN cell ratio of 1∶100. After 4 days, the percentages of proliferating (CFSE^lo) CD4⁺ and CD8⁺ T cells were determined by flow cytometry (A and B). The percentages of IFN-γ (upper panel) and TNF (lower panel) -producing CD4⁺ (C and D) and CD8⁺ (E and F)) T cells within the proliferating (CFSE^lo) population were also assessed. Shown are the representative histogram (A) and dot (C and E) plots of individual animals within the group and bar graphs (B, D and F) showing the means +/− SE of all the animals (3–4 mice) within the group. The absolute numbers of CD11c⁺MHCII⁺ dendritic cells in the draining lymph nodes of high and low dose infected mice were also determined by flow cytometry following Collagenase/Dispase digestion (G). Results presented are representative of 3 independent experiments (n = 3–4 mice/group) with similar results. *, p<0.05; **, p<0.01; ***, p<0.001.