Abstract
MAIT cells are unconventional innate-like T lymphocytes contributing to host immune protection against Mycobacteria tuberculosis (Mtb) infection. CD4- MAIT cells play a major role in immune protection against tuberculosis (TB), however, the role of CD4+ MAIT cells was elusive due to their low abundance. We firstly investigated the frequency and functions of CD4+ MAIT cells in pulmonary tuberculosis (PTB) patients before and after anti-TB treatment. We found that the frequency of Mtb-reactive CD4+ MAIT cells and IFN-γ, granzyme B (GrzB), CD69 expression on them were increased while LAG-3+ cells of them were decreased in PTB patients. After the treatment, the frequency of Mtb-reactive CD4+ MAIT cells and CD69, IFN-γ, GrzB expression on them were decreased while LAG-3 increased. The results indicated the expression profile is distinct between CD4+ MAIT cells and CD4- MAIT cells in PTB patients, the increased IFN-γ and GrzB expression of CD4+ MAIT cells play a role in anti-TB immunity.