Fig. 2.

Immune response to SARS-CoV-2. The scheme shows the main cells and cytokines involved in the immune defense mechanism against COVID-19 described in this review. SARS-CoV-2 severe acute respiratory syndrome coronavirus 2; NK cell natural killer cell; Th 17 T helper type 17; IL-1 Interleukin 1; IL-6 Interleukin 6; IL-8 Interleukin 8, IL-21 Interleukin 21, TNF-β tumor necrosis factor β, MCP-1 monocyte chemoattractant protein-1, DPP4 dipeptidyl peptidase-4; S protein spike glycoprotein; TLR-3 tool-like receptor—3; TLR-4 tool-like receptor—4; TLR-7 tool-like receptor—7; TLR-9 tool-like receptor—9; MyD88 myeloid differentiation factor-88; NF-kB nuclear factor kappa B; IRF interferon regulatory factors. Red lines refer to inhibitory effects. Green lines refer to activating effects.

Adapted from Li et al. and Yi et al. [2, 10]