The results of cytokine secretion (pg/mL) were statistically analyzed for significant differences between spontaneous secretion and secretion in response to various antigens using the Mann-Whitney U-test. P-values of <0.05 were considered significant. Spontaneous secretion of various cytokines by PBMCs of TB patients in the

absence of exogenously added mycobacterial antigens varied considerably, both with respect to the percentages of donors Selleck LDK378 secreting detectable concentrations of various cytokines, as well as their absolute concentrations. For example, detectable concentrations of IL-6 and IL-8 were secreted by PBMCs from all patients, whereas detectable concentrations of IL-2 and IL-10 were secreted by PBMCs from <50% of patients (Fig. 1a–c). With respect to the absolute concentrations of each cytokine secreted

into the culture supernatants, the median concentration was highest for IL-8 (5157 pg/mL), followed by IL-6 (225 pg/mL), IL-5 (157 pg/mL), TNF-α (112 pg/mL), IL-4 (51 pg/mL), IFN-γ (18 pg/mL), TNF-β (10 pg/mL), IL-1β (14 pg/mL), IL-10 (<6.9 pg/mL), and IL-2 (<8.9 pg/mL) (Fig. 1a–c). Spontaneous secretion of one or more Th1 and Th2 cytokines by PBMCs was observed in the majority (60% and 94%, respectively) of TB patients included in the study (Fig. 1b,c). Quantitation of proinflammatory cytokines in supernatants obtained from cultures with exogenously added mycobacterial antigens and pools of RD-peptides showed that only complex mycobacterial antigens induced secretion of IL1-β and TNF-α (Fig. 2a,c) (P < 0.05), and that relatively greater amounts of

these FK506 datasheet cytokines were secreted in response to whole-cell mycobacteria and MT-CW than MT-CF (P < 0.05). Moreover, all the complex mycobacterial antigens and peptide pools of RDs stimulated secretion of IL-6 (Fig. 3a,b), whereas, none of the mycobacterial antigens or RD peptides induced secretion of IL-8 (Fig. 3c,d). With respect to Th1 and Th2 cytokines, none of the mycobacterial antigens or peptide pools showed antigen-induced secretion of Th1 cytokine IL-2 (E/C < 2, P > 0.05) (Fig. 4a,b), whereas TNF-β was secreted in response to whole-cell M. tuberculosis, to MT-CF and MT-CW and peptide pools of RD1, RD6 and RD13 (Fig. 4c,d). Secretion of Th2 cytokines IL-4 and IL-5 was not detected in response to any of the complex mycobacterial antigens and RD peptides (E/C < 2, P > 0.05) (Fig. 5), except for weak IL-5 secretion (E/C = 2.6) in response to RD13 (Fig. 5d). Furthermore, antigen-induced secretion by PBMCs of IFN-γ and IL-10 was observed in response to all the preparations of complex mycobacterial antigens (E/C = 15 to 251, P < 0.05, Fig. 6a,c). However, variations in the concentrations of secreted IFN-γ and IL-10 were observed, MT-CF inducing the highest concentration of IFN-γ and the lowest concentration of IL-10 (P < 0.05), with an IFN-γ:IL-10 ratio of 14.5.