Effect of the -197G> A polymorphism on the production of IL-17A in response to hypervirulent strains of M. tuberculosis

Background: Th1/Th2 immunity is insufficient to control Mycobacterium tuberculosis (Mtb) infection, particularly against more virulent strains such as W-Beijing. Methods: Thirty patients with active tuberculosis (TBA) and 30 controls with latent tuberculosis (TBL) were included. The distribution of polymorphism rs2275913 was evaluated by real-time PCR. Mononuclear cells (MNCs) were stimulated with CFP-10 and ESAT-6 antigens and extracts of H37Rv, W-Beijing-HN878. Levels of IL-17, IFN-Γ were quantified by Luminex. Differences were assessed with Student t and U of Mann-Whitney and p values < 0.05 were significant. Results: No significant association of the 197G>A polymorphism with susceptibility to TBA was found. An effect of the -197G>A mutation was observed on the IL-17A expression rate. The MNCs of TBA patients with A/G genotype showed higher IL-17A (185 pg/mL) production relative to G/G patients (100 pg/mL, p = 0.008). This was not observed in individuals with TBL. The antigens of H37Rv and HN878 stimulated higher production of IFN-Γ in MNCs of patients with ATB (p < 0.05). Conclusion: The presence of the A allele at the -197 position of the IL-17A promoter conditions increased production of this cytokine in response to the W-Beijing-HN878 hypervirulent strain.