Study identifies autoimmune antibodies as culprit behind life-threatening blood clots in COVID-19

Illustration shows of a blood clot inside a cross-section of a blood vessel.
Credit: Stephanie King, University of Michigan


NHLBI-supported researchers are reporting that COVID-19 triggers the production of certain autoimmune antibodies in the blood and that these antibodies are the culprit behind the formation of potentially life-threating blood clots in people hospitalized with the disease.  Targeting these antibodies could lead to new treatments for COVID, they say. The study appears in Science Translational MedicineThe study was featured as the cover story of the Nov. 18 issue of the journal.

Blood structure formed in the blood of COVID-19 patients in the presence of autoantibodies. Credit: Reprinted with permission from AAAS.
Reprinted with permission from AAAS.

In the study, the researchers found about half of the patients who were very sick with COVID-19 were exhibiting a combination of high levels of both the dangerous antibodies and super-activated neutrophils, which are destructive, exploding white blood cells. Previously, the team was the first to report that patients hospitalized for severe COVID-19 had higher levels of neutrophil extracellular traps in their blood. These extracellular traps, also called Neutrophil Extracellular Traps or NETs, are sticky substances that are associated with increased blood clotting. To learn more, they studied the explosive neutrophils and the COVID-19 antibodies together in mouse models to see if this could be the dangerous combination behind the clots.

“Antibodies from patients with active COVID-19 infection created a striking amount of clotting in animals - some of the worst clotting we’ve ever seen,” said co-corresponding author Yogen Kanthi, M.D., an assistant professor at the Michigan Medicine Frankel Cardiovascular Center and a Lasker Investigator at the NHLBI, where he also serves as chief of the Laboratory of Vascular Thrombosis and Inflammation. “We’ve discovered a new mechanism by which patients with COVID-19 may develop blood clots.”

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