Different cytokine production and effector/memory dynamics of αβ+ or γδ+ T-cell subsets in the peripheral blood of patients with active pulmonary tuberculosis

Immunity to M.tuberculosis (MTB) infection consists of interactions between various T-cell subsets that control the infection and prevent further reactivation. We analysed the effector/memory T-cell dynamics and cytokines production in the peripheral blood of patients with pulmonary tuberculosis (TB). We observed that the frequency of CD4⁺ T-cell effectors was significantly increased during active TB, confirming a major role of this T-cell subset in TB immunity. Pre-terminally differentiated CD8⁺ T-lymphocytes were increased in the peripheral blood as well. In contrast, we observed a reduced number of effector mycobacteria-reactive γδ ⁺ T-lymphocytes with a specific defects in reacting to mycobacterial nonpeptidic antigens, suggesting that this innate response is rapidly lost during TB infection. Nevertheless, the frequency of γδ⁺ T-cells effectors in TB patients was higher than the αβ⁺ T-cell response to peptide from MTB-ESAT-6 protein and quantitatively similar to PPD reactivity. Thus, αβ⁺ and γδ⁺ T-cell differentiation and function are differently triggered by active TB infection.