Fig. 2.

Immunologic features of SARS-CoV-2-associated pathology. Abbreviations: NK cells, natural killer cells; APC, antigen-presenting cells. Explanatory notes: APC presents viral antigens to NK cells and CD8-positive cytotoxic cells to activate innate and adaptive immunity and to produce proinflammatory mediators (cytokines) [3]. The immune activation might become so intense that it can lead to exaggerated immune response (cytokine storm) [1], [23]. The cytokine storm can result in the damage of lungs, kidneys, heart, and/or liver [24]. The immunologic features of COVID-19 include also lower levels of T-lymphocytes, NK cells, and regulatory T-cells in patients with severe disease progression. An increased level of monocytes and macrophages in COVID-19 patients can also explain the elevation of proinflammatory cytokines [3].