FIG 3.

Verapamil and norverapamil limit the expansion of M. tuberculosis-specific T cells. PBMCs from PPD-positive subjects (n = 5) were labeled with CFSE and stimulated with M. tuberculosis WL for 7 days in the presence or absence of different concentrations of efflux pump inhibitors. On day 7, viable cells were estimated after counting of cells in aliquots mixed with trypan blue dye. In parallel, all cells were restimulated with phorbol myristate acetate (PMA) and ionomycin in the presence of GolgiStop for 2 h, and then stained for surface CD3 and intracellular IFN-γ. Flow-cytometric acquisition was performed by use of a BD LSR II instrument. (A and B) Effects of different concentrations of verapamil (A) and norverapamil (B) on the expansion of M. tuberculosis-specific T cells. *, P < 0.05; **, P < 0.01, by Mann-Whitney U test. Results are shown as means ± standard errors.