Figure 5. TLR2 expression on regulatory T cell populations does not affect their recruitment to the lungs.

Single cell suspensions from lungs and spleens of mice from Groups I and II were prepared at the indicated time points after Mtb challenge. Lung and spleen cells were stained with antibodies against CD4, CD45.1, and CD45.2 and then analyzed by flow cytometry. For both lung (A) and spleen (B) samples, lymphocytes were gated on, and then CD4⁺ cells were gated from this population. The number of CD4⁺ cells was determined by multiplying the percentage of gated cells by total lung cell number (left panel). Frequencies of Treg (middle panel) and Tconv (right panel) were determined by gating on CD45.1 and CD45.2 populations within the CD4⁺ gate and are presented as a percentage out of CD4⁺. Formalin-fixed, paraffin-embedded lung tissue was obtained at 9 weeks following infection. Sections from Groups I and II were stained with anti-Foxp3 and photomicrographs were taken at 20× original magnification. Sections are representative of 6 mice per group (C). Bacterial burden in the lungs was determined by plating serial dilutions of lung homogenates onto 7H11 agar plates (D). Data include 6 mice per group and are presented as mean ± SEM. No significant differences were observed between the two groups for all the tested parameters.