The presence of M. tuberculosis during Mo differentiation towards dendritic cells determines their ability to polarize antimycobacterial TH clones

BALBOA L; LABORDE E; SCHIERLOH P; MUSELLA R; DE CASADO GS; PALMERO D; SASIAIN MC

Whistler

Congreso; Tuberculosis: Understanding the Enemy; 2013

Keystone Symposia on Molecular and Cellular Biology

The success of Mycobacterium tuberculosis (Mtb) infection depends mainly on its ability to elude host immune responses. The development of TH1 cells is crucial for mounting an effective acquired immune response because IFN-γ activates the killing mechanisms of infected macrophages. As dendritic cells (DC) polarize T cells profiles, it is reasonable to settle that Mtb may interfere DC generation leading to immune evasion. This escape mechanism becomes relevant given that the major DC subset involved in mycobacterial infections are considered to be monocyte (Mo)-derived DC or ?inflammatory DC?. Previously we have demonstrated that the contact between Mtb and Mo leads to the impairment of DC differentiation, generating a cell population (called MtbDC) characterized by a poor capacity to induce specific anti-mycobacterial T clones proliferation. This MtbDC displayed low levels of CD1 molecules expression which accounts for the reduced specific CD restricted-T cells proliferation response. In this work, we evaluated the ability of MtbDC to polarized specific antimycobacterial TH cells. For that, we differentiated Mo from healthy donors PPD+ into DC by culturing them with IL-4 and GM-CSF in the presence (MtbDC) or not (DC) of Mtb for 6 days. Then, cells were stimulated with Mtb and the production of cytokines was determined by ELISA and by intracellular labeling with conjugated-antibodies followed by flow cytometry. Finally, we analyzed the cytokines profile of CFSE-proliferating CD4+ T cells activated by Mtb-matured MtbDC or DC by flow cytometry. We observed that MtbDC secreted higher levels of IL-10 and lower of IL-12 in response to Mtb than DC (p