The roles of multifunctional CD4 T cells in human tuberculosis are not well defined. In this study, we found that patients with tuberculosis had decreased PMA/ionomycin stimulated multifunctional CD4 T cells, and increased Mycobacterium tuberculosis antigen-specific multifunctional CD4 T cells, when compared to individuals with latent tuberculosis infection and healthy controls. PMA/ionomycin stimulated IFN-γ+IL-2+TNF-α+ CD4 T cell responses were decreased in patients with smear-positive tuberculosis compared to those with smear-negative tuberculosis. The percentage of IFN-γ+IL-2+TNF-α+ CD4 T cells in smear positive tuberculosis patients negatively correlated with the grade of sputum smear Acid-Fast Bacilli and high-resolution computed tomography score. Therefore, our findings argue against the notion that Mycobacterium tuberculosis antigen-specific multifunctional Th1 responses in peripheral blood can serve as correlates of protective immunity against tuberculosis; they suggest that the decrease in PMA/ionomycin stimulated IFN-γ+IL-2+TNF-α+ CD4 T cells may be applied for clinical diagnosis of active tuberculosis.

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