ABSTRACT
The SARS-CoV-2 virus causes various conditions, from asymptomatic infection to the fatal coronavirus disease 2019 (COVID-19). An intact immune system can overcome SARS-CoV-2 and other viral infections. Defective natural, mainly interferon I- and III-dependent, responses may lead to the spread of the virus to multiple organs. Adaptive B- and T-cell responses, including memory, highly influence the severity and outcome of COVID-19. With respect to B-cell immunity, germinal centre formation is delayed or even absent in the most severe cases. Extrafollicular low-affinity anti-SARS-CoV-2 antibody production will occur instead of specific, high-affinity antibodies. Helper and CD8+ cytotoxic T-cells become hyperactivated and then exhausted, leading to ineffective viral clearance from the body. The dysregulation of neutrophils and monocytes/macrophages, as well as lymphocyte hyperreactivity, might lead to the robust production of inflammatory mediators, also known as cytokine storm. Eventually, the disruption of this complex network of immune cells and mediators leads to severe, sometimes fatal COVID-19 or another viral disease.
Subject(s)
COVID-19 , Virus Diseases , Humans , SARS-CoV-2 , Adaptive Immunity , Antibodies, ViralABSTRACT
Coronavirus disease 2019 (COVID-19) displays tremendous inter-individual variability, ranging from asymptomatic infections to life-threatening illness. Although more studies are needed, a picture has begun to emerge that variability in the immune system components is a main contributor to the heterogeneous disease courses. Here, we provide a concept for the interaction of the innate and adaptive immune systems with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to link the observations that have been made during the first two years of the pandemic. Inborn errors of, and autoantibodies directed against, type I interferons, dysregulated myeloid response, hyperinflammation, lymphopenia, lymphocyte impairment, and heterogeneous adaptive immunity to SARS-CoV-2 are discussed, as well as their impact in the course of COVID-19. In addition, we will also review part of the key findings that have helped define and delineate some of the essential attributes of SARS-CoV-2-specific humoral and cell-mediated immune memory. Orv Hetil. 2022; 163(20): 774-787.