New Study: How COVID-19 may trigger dangerous blood clots

How COVID-19 may trigger dangerous blood clots | Science News Clots may stem from net-casting immune cells that, instead of fighting a coronavirus infection, capture red blood cells and platelets. Helen Thompson Science News

Some of COVID-19’s dangerous blood clots may come from the immune system attacking a patient’s body rather than going after the virus, a new study suggests.

It’s known that excessive inflammation from an overactive immune response can spur the clots’ formation in severely ill patients (SN: 6/23/20). Now researchers are teasing out how. Some of that clotting may come from auto-antibodies that, instead of recognizing a foreign invader, go after molecules that form cell membranes. That attack may prompt immune cells called neutrophils to release a web of genetic material geared at trapping virus particles outside of the cells.

“Presumably in the tissues, this is a way to control infections,” says Jason Knight, a rheumatologist at the University of Michigan in Ann Arbor. “But if you do it in the bloodstream, it’s very triggering of thrombosis,” or clotting.

That may be what happens in some COVID-19 patients, Knight, cardiologist Yogen Kanthi of the National Institutes of Health in Bethesda, Md., and their colleagues report November 2 in Science Translational Medicine. With COVID-19, blood clots in the lungs have been a significant cause of death, Kanthi says. And some blood clots may form when the webs trap red blood cells and platelets, creating a sticky clump that can clog blood vessels. ...

Studies have revealed that some auto-antibodies can interfere with the immune response to viruses (SN: 9/25/20). Some preliminary work further suggests that auto-antibodies that bind to a variety of targets in the host may be a common feature in severely ill COVID-19 patients....