Increased frequency of CD4+CD25+FoxP3+ circulating regulatory T cells (Treg) in tuberculous patients

BackgroundCD4+CD25+FoxP3+ circulating regulatory T cells (Treg) play a fundamental role in the control of immune responses by down-regulating the function of effector CD4+ or CD8+ T cells. Active suppression by Treg might be important in controlling immune responses against Mycobacterium tuberculosis (Mtb). This study was conducted to evaluate the cellular immune response to Mtb, by evaluation of Treg cells in peripheral blood mononuclear cells (PBMCs) from patients with active pulmonary tuberculosis (PTB), patients with tuberculous pleurisy (TP) and healthy positive PPD persons as control, then evaluation after 6 months of anti-TB therapy, also evaluation of Treg cells in pleural fluid mononuclear cells (PFMCs) from patients with tuberculous pleurisy (TP). We compared the frequency of CD4+CD25+FoxP3+ circulating regulatory T cells (Treg) in 20 patients with active pulmonary TB (PTB), 15 tuberculous pleurisy (TP) and 20 control latent tuberculosis.ResultsTreg frequencies in peripheral blood were significantly higher in patients with PTB and TP than in the control group (p < 0.001). Treg frequencies were significantly higher in pleural effusions than in peripheral blood in the same group (p < 0.001). Treg frequencies in peripheral blood were significantly decreased after 6 months of anti-TB treatment (p < 0.001).ObjectivesImmune regulatory mechanisms may limit the immunopathologic condition of infection with M. tuberculosis and suppress cellular immune responses in the host. We investigated the CD4+CD25+FoxP3+ circulating regulatory T cells (Treg) in patients with pulmonary tuberculosis, tuberculous pleurisy and latent TB, and the frequencies of CD4+CD25+FoxP3+ T-cells after anti-TB therapy.ConclusionMTB infection is associated with an increase in the frequency of CD4+CD25+FoxP3+ Treg in the blood of PTB and TP, in the pleural fluid of TP, decrease in the frequency after anti-TB therapy.