Blood clots continue to wreak havoc for patients with severe COVID-19 infection, and a new study explains what may spark them in up to half of patients.

The culprit: An autoimmune antibody that’s circulating in the blood, attacking the cells and triggering clots in arteries, veins, and microscopic vessels.

Blood clots can cause life-threatening events like strokes. And, in COVID-19, microscopic clots may restrict blood flow in the lungs, impairing oxygen exchange.

Outside of novel coronavirus infection, these clot-causing antibodies are typically seen in patients who have the autoimmune disease antiphospholipid syndrome.

The connection between autoantibodies and COVID-19 was unexpected, says the co-corresponding author.

Co-corresponding author Jason Knight, M.D., Ph.D., a rheumatologist at Michigan Medicine, has been studying antiphospholipid syndrome antibodies in the general population for years. “Half of the patients hospitalized with COVID-19 were positive for at least one of the autoantibodies, which was quite a surprise,” says Knight.

In the new Science Translational Medicine publication, they 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.

In April, the team was the first to report that patients hospitalized for severe COVID-19 had higher levels of neutrophil extracellular traps in their blood.

“We’re now investigating how long these antibodies remain in circulation after recovery from the novel coronavirus,” Knight says.

Source: https://labblog.uofmhealth.org/lab-report/new-cause-of-covid-19-blood-clots-identified