Patients who may have lupus typically undergo an “ANA” test to detect anti-nuclear antibodies (ANAs). Lupus Research Alliance Distinguished Innovator Award recipient Dr. Shu Man Fu of the University of Virginia and colleagues found that people who don’t have lupus also produce ANAs. This suggests that patients can not be diagnosed with lupus just because they have these antibodies.

Antibodies are proteins that normally provide protection against infections. But patients with lupus make antibodies, including ANAs, that target their own cells. ANAs home in on molecules from the nucleus, our cells’ command center. Patients who test positive for ANAs are sometimes diagnosed with lupus even if they have no symptoms of the disease, Dr. Fu said.

“This situation creates anxiety for patients and their families and confuses the results of clinical trials for therapies for treating lupus.”

To find out more about how ANAs form, Dr. Fu and his team studied immune cells from mice and blood samples from people who did not have lupus. Their results show that when the immune system tries to fight off bacteria and viruses, it normally produces ANAs and other antibodies that can target the body’s own cells. That means doctors can not use ANAs alone to diagnose lupus, Dr. Fu said. He added that now researchers also need to figure out why so many people who produce ANAs don’t develop lupus.

The scientists reported their findings in Annals of the Rheumatic Diseases.