Gene

Complement system

Biology

Complement (music)

Immunity

Biochemistry

Immunology

Complementation

Immune system

Respiratory failure

Internal medicine

Respiratory system

Medicine

Innate immune system

Alternative complement pathway

Phenotype

Proceedings of the National Academy of Sciences

Significance The new SARS-CoV-2 pandemic leads to COVID-19 with respiratory failure, substantial morbidity, and significant mortality. Overactivation of the innate immune response is postulated to trigger this detrimental process. The complement system is a key player in innate immunity. Despite a few reports of local complement activation, there is a lack of evidence that the degree of systemic complement activation occurs early in COVID-19 patients, and whether this is associated with respiratory failure. This study shows that a number of complement activation products are systemically, consistently, and long-lastingly increased from admission and during the hospital stay. Notably, the terminal sC5b-9 complement complex was associated with respiratory failure. Thus, complement inhibition is an attractive therapeutic approach for treatment of COVD-19.

Systemic complement activation is associated with respiratory failure in COVID-19 hospitalized patients