Fig. 6

ESAT-6 inhibits the expression of cytokines IL-12, TNF-α, and IL-10 in THP-1 macrophages via TLR2. A–C Total RNA was extracted from THP-1(A) cells 24 h after infection of M. tb, M. tb with different concentrations of ESAT-6. mRNA levels of IL-12, TNF- α, and IL-10 were detected by real-time fluorescence quantitative PCR. D, E THP-1(A) cells were infected by H37Ra for one hour, then treated with blocking anti-TLR2 antibody for 30 min, and finally treated with 5 μg/ml ESAT-6 for 24 h. Protein levels of IL-12, TNF-α, and IL-10 were detected by ELISA. The experiments were repeated at least three times and the data represented in the figure are the mean ± SEM of three independent experiments. *, **, *** and **** indicate p < 0.05, p < 0.01, p < 0.001 and p < 0.0001, respectively, compared to the M. tb-infected group