Increased blood monocytic myeloid derived suppressor cells (MDSCs) and
decreased activated T lymphocytes in COVID-19 patients
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.