A multi-disciplinary team of researchers evaluated blood serum samples using a technique called immunofluorescence to detect ANA in 4,754 individuals from the 1994-2004 National Health and Nutrition Examination Survey (NHANES). The overall prevalence of ANA in the population was 13.8 percent, and was found to be modestly higher in African-Americans compared to whites. ANA generally increased with age and were higher in women than in men, with the female to male ratio peaking at 40-49 years of age and then declining in older age groups.
"The peak of autoimmunity in females compared to males during the 40-49 age bracket is suggestive of the effects that the hormones estrogen and progesterone might be playing on the immune system," said Linda Birnbaum, Ph.D., director of NIEHS and an author on the paper.
The paper also found that the prevalence of ANA was lower in overweight and obese individuals than persons of normal weight. "This finding is interesting and somewhat unexpected," said Edward Chan, Ph.D., an author on the study and professor of the Department of Oral Biology at the University of Florida.
"It raises the likelihood that fat tissues can secrete proteins that inhibit parts of the immune system and prevent the development of autoantibodies, but we will need to do more research to understand the role that obesity might play in the development of autoimmune diseases," said Minoru Satoh, M.D., Ph.D., another author on the study and associate professor of rheumatology and clinical immunology at the University of Florida.
The researchers say the paper should serve as a useful baseline for future studies looking at changes in ANA prevalence over time and the factors associated with ANA development. The paper is the first in a series analyzing these data from the NHANES dataset, and exploring possible environmental associations with ANA.
|Contact: Robin Mackar|
NIH/National Institute of Environmental Health Sciences