Increased frequencies of T helper type 17 cells in tuberculous pleural effusion.

Th17 cells have emerged as an important mediator in inflammatory and autoimmune diseases. Recent studies suggest a potential impact of Th17 cells on tuberculosis (TB) infection. This study was designed to investigate the possible involvement of Th17 cells in tuberculous pleural effusion. Compared with healthy volunteers, patients with TB had a higher proportion of Th17 cells in peripheral blood mononuclear cells (PBMCs). Moreover, the percentage of Th17 cells in pleural effusions of TB patients was obviously higher than that in PBMC from TB patients or healthy controls. Furthermore, the mRNA and protein expression levels of IL-17 and IL-6 were significantly increased in the patients with tuberculous pleural effusion, while expression level of TGF-β was decreased in the pleural effusion. Correlation analysis showed a significant correlation between IFN-γ concentrations and the frequencies of Th17 cells in tuberculous pleural effusion. These results indicate that Th17 cells may contribute to the immunopathogenesis of tuberculous pleural effusion.