A new study estimates that more than 32 million people in the United States have antibodies that can attack the body’s own tissues, potentially resulting in inflammation and autoimmune diseases, such as type 1 diabetes, lupus, and rheumatoid arthritis. The study, conducted by researchers with the National Institute of Environmental Health Sciences and the University of Florida in Gainesville, appears online in Arthritis & Rheumatism.
Antibodies are Y-shaped proteins produced by B cells that typically help the body fight off infections. But sometimes, for reasons not well understood, an individual’s B cells produce autoantibodies, antibodies that attack the body’s tissues rather than invading pathogens. The researchers evaluated blood serum samples from 4754 individuals participating in the 1994-2004 National Health and Nutrition Examination Survey to determine the prevalence of antinuclear antibodies (ANAs), the most common type of autoantibody.
The investigators found that the overall prevalence of ANAs in this population was 13.8%, which suggests that ANAs could be found in more than 32 million people in the United States. They also found that prevalence of ANAs generally increases with age and that ANA prevalence was significantly higher in women than in men (17.8% vs 9.6%) and modestly higher in non-Hispanic blacks compared with other racial/ethnic groups.
An interesting and unexpected finding was a lower prevalence of ANAs in overweight and obese people (particularly women) compared with persons of normal weight. The researchers speculated in a statement that fat tissues can secrete proteins that inhibit parts of the immune system and prevent the development of autoantibodies, but noted that more research is needed to understand the role that obesity might play in the development of autoimmune diseases. They also found that alcohol consumption and smoking (or having a smoking history) were not associated with ANA.
Previous studies have shown that ANAs can develop many years before the clinical appearance of autoimmune disease; ANAs are frequently measured biomarkers for detecting autoimmune diseases, but their presence does not necessarily mean a person will develop an autoimmune disease. The researchers said their findings “should be kept in mind by physicians when assessing ANA results and will serve as a useful baseline for future investigations of changes in ANA prevalence over time and the factors associated with their development.”