CHARACTERIZATION OF INTERLEUKIN-17 PRODUCING CELLS IN THE PERIPHERAL BLOOD OF PATIENTS WITH TUBERCULOSIS

Abstract

Abstract Tuberculosis (TB), an infection caused by Mycobacterium tuberculosis, is one of the ten main causes of death by infectious disease. When the mycobacteria are inhaled, they interact with immune cells in the respiratory tract in a specialized structure known as granuloma. Interleukin 17 (IL-17) contributes to formation and size of the granuloma, and it correlates with the recruitment of neutrophils. It has been demonstrated that other innate lymphocytes, such as Tγδ cells, contribute to the production of IL-17 during TB. Innate lymphoid cells (ILCs) are other innate lymphocytes that are classified into groups (ILC1, ILC2 and ILC3) according to their cytokine patterns. ILC3 produce IL-17, but it is not known if these cells participate in the response to TB infection. We evaluated, by flow cytometry, the frequency and IL-17 production of Th, Tgd, NK and ILCs (ILC1, ILC2 and ILC3) in the peripheral blood of healthy individuals (negative and positive for the Quantiferon [QTF] test, which detects latent TB), and of patients with active pulmonary TB. The numbers of Th cells, NK cells and ILCs (ILC1, ILC2 and ILC3) were decreased in TB patients, compared to healthy individuals. Peripheral blood was stimulated with M. tuberculosis soluble extract (MTSE) for 5 h in the presence of brefeldin A. After stimulation, Th cells from QTF-positive healthy individuals and TB patients produced IL-17. Tγδ cells also produced IL-17, although the percentage of these cells did not change after activation with MTSE. In some cases, NK, ILC2 and ILC3 from TB patients produced IL-17, but this production did not change after MTSE activation. These results indicate that Th and Tγδ cells contribute to IL-17 production during TB. This project was funded by SIP-IPN-México (20180254).