**5. Conclusions**

The role of IL-18, its binding protein IL-18BP, and IFN-γ in the development of the immune response against mycobacteria was confirmed by observing the increased level of the expression of these genes in the group of patients with active pulmonary TB. The reduced expression of IL-18R gene in healthy individuals with latent TB infection can, at least partially, prevent the development of a pathological inflammatory reaction and promote the maintenance of homeostatic conditions between host immunity and *M.tb* infection. In our future studies, we plan to test the expression of other genes that are tightly co-regulated with the IL-18 pathway.

**Author Contributions:** Conceptualization: S.W., M.D.; Data curation: S.W., G.K.; Formal analysis: M.D.; Funding acquisition: S.W., M.D.; Investigation: S.W.; Methodology: S.W., M.S.; Supervision: G.K., W.R., M.D.; Validation: S.W.; Visualization: S.W.; Writing original draft: S.W., W.R., M.S., M.D. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the National Science Centre grants no 2015/19/N/NZ6/01385 and 2016/21/B/NZ7/01771.

**Conflicts of Interest:** The authors declare that there is no conflict of interest regarding the publication of this article.
