1a). With respect to Th1 and Th2 cytokines, none of the complex mycobacterial antigen or peptide pools induced secretion of Th1 cytokine IL-2 (Fig. 4) or Th2 cytokines IL-4 and IL-5, except for weak IL-5 secretion (E/C = 2.6) in response to RD13 (Fig. 5). In the face of of our observation of positive antigen-induced proliferation responses with complex mycobacterial antigens and several RD peptides, as reported previously (27), our inability to detect antigen-induced secretion of IL-2 and IL-4, which are growth factors
for cells of immune lineage, Dabrafenib price indicates their utilization by proliferating cells in PBMCs (50,51). In addition, this study supports previous observations of a lack of mycobacterial antigen-induced secretion of IL-2 and IL-5 by PBMCs of TB patients Torin 1 supplier (6, 52, 53). A lack of secretion of IL-2 and IL-5 by PBMCs in response to mycobacterial antigens has also been reported in healthy subjects (6, 52). In contrast to the lack of secretion of IL-2, IL-4 and IL-5, the other
two Th1 and Th2 cytokines, namely IFN-γ and IL-10, were secreted by PBMCs of TB patients in response to all the preparations of complex mycobacterial antigens (Fig. 6a,c). However, variations in the concentrations of these cytokines were observed, MT-CF inducing the highest concentration of IFN-γ and the lowest concentration of IL-10; whereas, whole cells and cell walls of M. tuberculosis induced higher concentrations of IL-10 with IFN-γ:IL-10 ratios of <1, and whole cells of M. bovis BCG induced equally high concentrations of both cytokines. It is important to avoid antigens stimulating high concentrations of IL-10 when designing new vaccines against TB, because IL-10 compromises the ability of protective cells and cytokines
by down-regulating the production of IFN-γ, TNF-α, IL-1 and IL-12 (54). Furthermore, IL-10 interferes Carbohydrate with the functions of macrophages, T-cells and natural killer cells and helps mycobacteria to survive intracellularly, despite abundant production of IFN-γ (55). On the contrary, the absence of IL-10 accelerates mycobacterial clearance (56). Thus, our findings support previous suggestions that culture filtrate antigens of M. tuberculosis may be suitable for developing new vaccines against TB (57, 58). PBMCs secreted mainly IFN-γ in the presence of peptide pools of RD1, RD5, RD7 and RD9, without detectable concentrations of IL-10 (Fig. 6b,d); whereas mainly IL-10 was secreted in the presence of peptide pools of RD12, RD13 and RD15, and both IFN-γ and IL-10 were secreted in the presence of peptide pools of RD4 and RD6 (Fig. 6b,d).