Treg activity in the peripheral blood of early and serofast syphilis patients.

<p>(<b>A</b>) Peripheral blood mononuclear cells (PBMC) were stained for flow cytometric analysis and lymphocytes were gated according to forward and side scatter characteristics. Representative plots show the gates of CD4⁺ CD25^high and CD4⁺ Foxp3⁺ T cells in the lymphocyte gate. CD25 and Foxp3 expression among CD4⁺ T cells are also shown. (<b>B</b>) The percentage of CD25^high and Foxp3⁺ among CD4⁺ T cells in peripheral blood of healthy controls, and in patients with primary, secondary, latent and serofast syphilis. Individual frequencies for every patient analyzed are shown. (<b>C</b>) CD4⁺ CD25⁺ T cells and CD4⁺ CD25⁻ T cells were purified from peripheral blood of healthy donors, and patients with primary, secondary, latent and serofast syphilis. The mean percent inhibition of the proliferative response by CD4⁺ CD25⁺ T cells derived from three to five individuals per group is shown. <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002528#s3" target="_blank">Results</a> are representative of three independent experiments. (<b>D</b>) Serum concentrations of TGF-β were measured in healthy controls, and in patients with primary, secondary syphilis, latent, and serofast syphilis. <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002528#s3" target="_blank">Results</a> represent the mean or the mean ± SEM. (<b>E</b>) Correlation of serum TGF-β concentration with circulating CD4⁺ CD25^high Treg frequencies in syphilis patients (n = 176). Each dot represents an individual patient. B, Kruskal-Wallis test; C and D, One-way ANOVA; E, Pearson's correlation. *, P<0.05; **, P<0.01; ***, P<0.001.