Treg cells limit inflammation and increase the differentiation of Th1, Th2 and Th17 cells.

<p>Rag1<sup>-/-</sup> mice were reconstituted with different T cell subpopulations, infected with <i>P</i>. <i>brasiliensis</i> and sacrificed at the time points indicated. Lungs were excised and single cells were stained as described in Materials and Methods section. (A) Number of total leukocytes, lymphocytes, macrophages and granulocytes in the lungs of infected Rag1<sup>-/-</sup> mice given Treg cells, CD4<sup>+</sup>Foxp3<sup>-</sup> T cells or CD4<sup>+</sup>Foxp3<sup>-</sup> T cells + Treg cells. (B) Frequency and number of CD4<sup>+</sup>CD69<sup>+</sup>Foxp3<sup>-</sup> T lymphocytes and Treg cells in the lungs of infected Rag1<sup>-/-</sup> mice previously reconstituted with Treg cells, CD4<sup>+</sup>Foxp3<sup>-</sup> T cells or CD4<sup>+</sup>Foxp3<sup>-</sup> T cells + Treg cells. (C-E) Numbers of CD4<sup>+</sup> T lymphocytes producing IFN-γ, IL-17 and IL-4 in reconstituted and infected Rag1<sup>-/-</sup> mice. (F) Quantitative PCR analysis of major transcription factors of T cells in the lungs of Rag1<sup>-/-</sup> mice, as determined by RT-PCR after 2 and 6 weeks post-infection. Rag1<sup>-/-</sup> mice were reconstituted with the different T cell subpopulations or vehicle only, infected with <i>P</i>. <i>brasiliensis</i> or left uninfected, and sacrificed after 2 and 6 weeks. Lungs were removed, RNA was extracted, reverse transcribed and the amplified cDNA was used for RT-PCR, as described previously. All bars indicate mean ± SD from at least 5 mice per group and are representative of three independent experiments (* <i>p</i> < 0.05; **<i>p</i> < 0.005; ***<i>p</i> < 0.001).</p>