ABSTRACT
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may produce a systemic disease, the coronavirus disease-19 (COVID-19), with high morbidity and mortality. Even though we do not fully understand the interaction of innate and adaptive immunity in the control and complications of the viral infection, it is well recognized that SARS-CoV-2 induces an immunodepression that impairs the elimination of the virus and favors its rapid dissemination in the organism. Even less is known the possible participation of inhibitory cells of the innate immune system, such as the myeloid-derived suppressor cells (MDSCs), or the adaptive immune system, such as the T regulatory cells (Tregs). That is why we aimed to study blood levels of MDSCs as well as lymphocyte subpopulations including Tregs, and activated (OX-40+) and inhibited (PD-1) T lymphocytes in patients with COVID-19 in comparison with data obtained from control donors. We have found that 12 hospitalized patients with COVID-19 and no health history of immnosuppression had a significant increase in the number of peripheral monocytic MDSCs, but not Tregs, as well as an increase in the number of inhibited or exhausted T cells, whereas the number of activated T cells was significantly decreased compared with that from 20 healthy controls. Moreover, there was a significant negative correlation (- 0.791) between the number of M-MDSC and the number of activated T cells. Therefore, SARS-Cov-2 seems to recruit MDSCs, and these inhibitory cells may contribute to the immunosuppression observed in patients with COVID-19.