Fig. 4.

The immune response in the COVID-19 symptomatic patients. The symptomatic patients produce a high amount of GRO-α or CXCL1, which increase neutrophil infiltration in the lung via enhancing luminal and sub-endothelial cell neutrophil crawling. The increased G-CSF and M-CSF in these patients also increase neutrophil and monocyte infiltration in the lungs and their survival and differentiation. The increased IL-6 levels also increase the neutrophil and monocyte infiltration in the lungs. The increased TRAIL levels prevent the resting and active B cell apoptosis, induce apoptosis among CD4⁺T and CD8⁺T cells, and neutrophils to prevent the exaggeration of inflammation and the lung injury. These patients have higher neutralizing Abs in their convalescent stage than asymptomatic individuals.