YERSINIA ENTEROCOLITICA-INDUCED Mo-MDSC SUPPRESS T-CELL PROLIFERATION THROUGH A NITRIC OXIDE-DEPENDENT MECHANISM

LEPORATI M; DAVICINO RC; DI GENARO MS; ELIÇABE J

Congreso; LXVIII Reunión Anual de la Sociedad Argentina de Inmunología; 2020

Sociedad Argentina de Inmunología

Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immature myeloid cells that have a potent ability to suppress T-cell responses. Monocytic MDSC (Mo-MDSC) and polymorphonuclear MDSC (PMN-MDSC) are the main subsets of MDSC. Yersinia enterocolitica (Ye) is a Gram-negative bacterium that causes food-borne gastrointestinal diseases. In previous studies, we demonstrated that Ye oral infection induces the expansion and accumulation of MDSC. The purpose of this work was to investigate the MDSC sub-population that exerts the suppressive activity and the underlying mechanism of suppression. Mice of the strain C57BL/6 were infected with Ye WAP-314 serotype O:8. On day 5 post-infection (p.i), MDSC were analyzed in bone marrow (BM), mesenteric lymph nodes (MLN) and spleen by flow cytometry. Furthermore, Mo-MDSC and PMN-MDSC were purified from the spleen of infected mice and their suppressor activity was evaluated in co-cultures with purified T cells. Nitric oxide (NO) production was analyzed by nitrite quantification in culture supernatants. We found that MDSC expanded in BM and accumulated in MLN and the spleen of infected mice, in contrast with uninfected mice (p