The role of Vdelta2+T-cells in patients with active Mycobacterium tuberculosis infection and tuberculin anergy.

SETTING: Tuberculosis (TB) is one of the most common major infectious diseases. In humans, acquired protective immunity to Mycobacterium tuberculosis depends on T-cells and involves multiple T-cell subsets; however, the pathways used by T-cells to restrict the growth of M. tuberculosis are poorly understood.
OBJECTIVE: To investigate the possible role of Vdelta2+T-cells and regulatory T-cells in the immune response to M. tuberculosis. As Vdelta2+T-cell function has been shown to be impaired in patients with M. tuberculosis infection, we investigated the percentage of perforin and Fas ligand (FasL) positive Vdelta2+T-cells and the possible role of activating and inhibitory natural killer (NK) cell receptors as well as that of regulatory T-cells in the control of tuberculin responsiveness.
RESULTS: Tuberculin-negative patients demonstrated decreased perforin expression and increased FasL expression, which could not be explained by dysregulation of NK cell receptor expression or altered regulatory T-cell function.
CONCLUSION: Altered cytotoxic capacity and apoptotic potential of Vdelta2+T-cells provide a plausible explanation for defective cellular immune functions in M. tuberculosis-infected anergic patients.