Discussion
In the present study, among 105 patients with severe COVID-19, 44.8%
patients (47/105) showed decreased CD4+T cells count
and the in-hospital death was markedly higher in patients with decreased
CD4+T cells count than in patients with normal
CD4+T cells count (42.6% vs 3.4%,P <0.001). In addition, our study found that increased
age, increased white blood cell count, and decreased platelet count were
associated with in-hospital death, which were similar with several
studies. Verity, et al. estimated that the total case fatality rate
increased with age, possibly because they often had other chronic
diseases4. Wang, et al. suggested that white blood
cell count and neutrophil count of dead patients were higher than those
of surviving patients, which may be related to cytokine storm caused by
the invasion of SARS-Cov-25. Meanwhile, A
meta-analysis showed that there was a significant reduction in platelets
in patients dying from COVID-19, and low platelet count was associated
with mortality in patients with COVID-19; The reason may be the decrease
of the number of pulmonary vascular beds and the change of morphology
that lead to deranged platelet defragmentation6.
Several recent studies indicated that T-lymphocytes1,7was reduced in most patients with COVID-19. It was believed that
SARS-CoV-2 may act mainly on lymphocytes, especially
T-lymphocytes2,8. At present, the potential mechanisms
undergoing CD4+T cells count decrease induced by
SARS-CoV-2 infection is still unknown. Researchers suggested the
decrease in the number of T-cells in patients with COVID-19 may be due
to the negative effects of high concentrations of TNF-α, IL-6, IL-10 in
serum on the survival or proliferation of T-cells7. In
addition, Previous studies have shown that, in SARS patients, the
formation of autoimmune antibodies or immune complexes induced by viral
infection and the use of steroids may play an important role in
lymphocytic decline9.
In conclusion, the main finding of this study is the high prognostic
value of decreased CD4+T cells count in patients with
severe COVID-19. Thus, in this acute-care setting,
CD+4 T cells count can provide early prognostic
information in patients with severe COVID-19.