Whole blood was cultured with PMA/ Ionomycin for 6 h and the net frequencies of CD4+ Th1, Th2 and Th17 cells determined. (A) Representative whole-blood intracellular cytokine assay flow data from a latent TB individual showing expression of Th1, Th2 and Th17 cytokines following PMA/ ionomycin stimulation. The plots shown are gated on CD3+CD4+ T cells. (B) Net frequency of CD4+ T cells expressing only mono –functional Th1, Th2 and Th17 cytokines is shown as bar graphs. (C) Net frequency of CD4+ T cells expressing dual –functional Th1, Th2 and Th17 cytokines is shown as bar graphs. The bar represents the geometric mean of the frequency of CD4+ T cells expressing the respective cytokine(s), and the error bar represents the 95% confidence interval in hookworm uninfected (LTB, n = 21) and hookworm infected (HW/LTB, n = 21) latent TB individuals. Net frequencies were calculated by subtracting baseline frequency from the antigen – induced frequency for each individual. P values were calculated using the Mann-Whitney test.