Immune system can cause broad damage in COVID-19

Antibodies are supposed to attack invading germs, but severely ill COVID-19 patients have so-called autoantibodies that mistakenly attack not just their own tissues and organs but even virus-fighting proteins produced by the immune system, new research shows.

Scientists studied 194 COVID-19 patients, including 55 with severe disease, plus a control group of 30 people without the virus. In the sickest patients, they found a high frequency of autoantibodies created by the immune system causing injury to the central nervous system, blood vessels, and connective tissues like cartilage, ligaments and tendons.

They also found a high prevalence of autoantibodies that interfere with substances involved in the functioning of the immune system itself, including cytokines and other “immunomodulatory” proteins. “The surprising extent of autoantibody reactivities” in these patients indicates that these mistakenly targeted antibodies are “an intrinsic aspect” of COVID-19.

The report was posted on medRxiv on Saturday ahead of peer review.