Increased frequency of CD4 + CD25 + FoxP3 + circulating regulatory T cells [Treg] in tuberculous patients

ABSTRACT

CD4 + 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 CDS + 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. Treg 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]. Immune 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. MTB 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