Figure 4.

The imbalance in T-cell immunity between severe and mild COVID-19. The dysregulation of T-cells includes imbalanced immune cell compartments and the expression of inhibitory molecules such as PD-1, Tim-3, and NKG-2A. The dynamic disease progression from mild to severe symptoms, which manifested with cytokine storm, was exhibited with distinct T subsets and T-cell responses. In mild COVID-19 cases, the Th1 subsets were higher than those in severe COVID-19 cases, leading to a strong CTL and macrophage phagocytes. However, in severe cases, Th2, Th17, and Treg subsets were comprised mainly of T-cells, together also with highly expressed inhibitory molecules, such as PD-1, TIM-3, and NKG2A. The image was created with BioRender.com.