SUMMARY
A better understanding of the innate and adaptive cells in the COVID-19
disease caused by the SARS-CoV-2 coronavirus is a necessity for the
development of effective treatment methods and vaccines. We studied
phenotypic features of innate and adaptive immune cells, oxidative
burst, phagocytosis and apoptosis. One hundred and three patients with
COVID-19 grouped according to their clinical features as mild (35%),
moderate (40.8%), and severe (24.3%) were included in the study.
Monocytes from all COVID-19 patients were CD16+pro-inflammatory monocytes. Neutrophils were mature and functional. No
defect has been found in ROS production of monocytes and neutrophils as
well as no defect in their apoptosis. As bridging cells of the innate
and adaptive immune system; the percentage of NK cells was in normal
range whereas the percentages of
CD3-CD8+CD56+innate lymphoid and CD3+CD56+ NK
like T cells were found to be high in the severe cases of COVID-19.
Although absolute numbers of all lymphocyte subsets were low and showed
a tendency for a gradual decrease in accord with the disease
progression, in all COVID-19 patients, the lymphocyte subset with the
most decreased absolute number was B lymphocytes, followed by CD4 + T
cells in the severe cases. The percentages of regulatory,
CD3+CD4-CD8-;
HLA-DR+CD3+ and
CD28-CD8+ cells were found to be
significantly increased. Importantly, we demonstrated spontaneous
caspase-3 activation and increased lymphocyte apoptosis. Altogether our
data suggest that SARS-CoV- 2 primarily affects lymphocytes not innate
cells. So that, it may interrupt the cross-talk between adaptive and
innate immune systems.