KYOTO, JAPAN More than 7% of individuals without any form of autoimmune disease possess elevated serum bullous pemphigoid 180 and/or BP230 autoantibodies on the commercially available enzyme-linked immunosorbent assay, according to testing of stored serum from 370 people.
These autoantibodies have been considered diagnostic for bullous pemphigoid, the most common cutaneous autoimmune bullous disorder, but that is clearly not the case, Dr. Nneka I. Comfrere of the Mayo Clinic in Rochester, Minn., reported at an international investigative dermatology meeting.
"I think there's not one test we can clearly rely on to make the diagnosis. What we've concluded at the Mayo Clinic is disease confirmation requires a correlation of multiple measures, including the clinical pattern, the presentation of disease, routine histopathology, and both direct and indirect immunofluorescence studies, as well as the ELISA [enzyme-linked immunosorbent assay], in order to ensure the highest diagnostic accuracy. Clearly, one cannot rely solely on the ELISA," she said.
Dr. Comfrere and her associates examined the prevalence of circulating BP180 and BP230 autoantibodies across the age spectrum of individuals who did not have bullous pemphigoid or any other autoimmune disease. They tested stored serum from patients aged 20 years to more than 90 years.
A positive test for one or both autoantibodies, defined by the manufacturer as a level of nine units or more, was detected in 7.4% of subjects. The prevalence did not vary by decade of life or by gender. Moreover, the geometric mean titer also remained similar across the decades, she said at a meeting of the European Society for Dermatological Research, the Japanese Society for Investigative Dermatology, and the Society for Investigative Dermatology.
Audience members raised the possibility that the presence of circulating autoantibodies in asymptomatic individuals might precede clinical manifestations of the disease, but the finding that prevalence of the autoantibodies was similar across the decades rather than peaking in the elderly argues against this, Dr. Comfrere noted.
The role of these autoantibodies in initiating and perpetuating the disease process remains unclear, she added. It's possible that the development of clinical bullous pemphigoid requires exogenous factors in susceptible individuals.