Fig. 3.

Mechanism of CRS in critically ill COVID-19 patients. a In severe case, increase in IFN-α, IFN- γ and TNF receptor gives rise to uncontrolled pro- and anti-inflammatory response. b The SARS-CoV-2 infects the alveolar type II cells, enhances permeability of these cells, and stimulates macrophages, neutrophils and other components of innate and adaptive immunity. This further impedes the IFN type I response and causes a rapid influx of neutrophils, monocytes/macrophages resulting in hypersecretion of cytokines, ultimately leading to ARDS and multiple organs failure. IFN; interferon, TNF; tumor necrosis factor