Myeloid-derived Suppressor Cell and Non-classical Monocyte Frequencies Are Directly Related to the Immunological Status of Patients With Active Tuberculosis

Abstract Alterations of myeloid cell populations have been reported in patients with tuberculosis (TB). Since myeloid-derived suppressor cells (MDSC) and non-classical monocytes (CD14+CD16+) seem to play an important role in TB, we studied the relationship between these cells and the immunological status of patients. TB patients were classified as high responders (HR-TB) or low responders (LR-TB) according to their T cell responses against a whole cell lysate of Mycobacterium tuberculosis (Mtb-Ag). Thus, LR-TB, individuals with severe disease, display a weaker immune response to Mtb compare to HR-TB, subjects with strong immunity against the bacteria. We observed that LR-TB presented higher percentages of CD14+CD16+ monocytes as compared to HR-TB and healthy donors (HD). Moreover, monocyte-like (M-MDSC) and polymorphonuclear-like MDSC (PMN-MDSC) were increased in TB patients as compared to HD. Furthermore, the proportion of M-MDSC of TB patients inversely correlated with the levels of IFN-γ released after Mtb-Ag stimulation. We also found that LR-TB displayed the highest levels of circulating M-MDSC. Interestingly, in LR-TB, the frequencies of non-classical monocytes and M-MDSC were restored after only three weeks of anti-TB treatment. Together, our findings show a direct relationship between the immunological status of TB patients and the levels of different circulating myeloid cell populations.