IL18 and tuberculosis: Following stimulation with PPD, production of all cytokines except IL-18 was significantly higher from TB cases compared to TST− contacts (Figure 1) while production of IFN-γ, IL-13 and IL-17 were all significantly higher in TST+ compared to TST− contacts (p = 0.0027; p = 0.0266 and p = 0.0105 respectively; Figs. 1A, E, F).