Increased prevalence of anti-DFS70 antibodies in young females: experience from a large international multi-center study on blood donors.

Background Isolated antibodies to DFS70 have been described in healthy individuals and are rarely found in patients with antinuclear antibody-associated autoimmune rheumatic diseases (AARD). However, no data is available on geographic differences in the prevalence of anti-DFS70 antibodies. We aimed to study the prevalence of anti-DFS70 antibodies in blood donor samples from several countries representing various ethnical backgrounds and geographic regions in the world. Methods Sera from apparently healthy blood donors (n≥300 per site) were collected in seven countries (USA, Italy, Spain, Germany, UK, Belgium and Brazil). All samples (n=2628) were tested for anti-DFS70 antibodies by QUANTA Flash DFS70 (Inova Diagnostics, Inc., San Diego, CA, USA). Results The prevalence of anti-DFS70 antibodies varied from 4/321 (1.2%, Italy) to 42/497 (8.5%, USA). Consequently, the prevalence of the antibodies was significantly higher in USA compared to all other countries (p<0.05). In addition, the prevalence in the combined cohort (all sites) was higher in young blood donors (<35 years; 5.0% vs. 2.7%; p=0.0017) and among females (4.5% vs. 3.0%; p=0.0446). However, when cohorts from different countries were corrected for age and gender, no significant difference between the countries were found. Conclusions This is the first study to analyze the prevalence of anti-DFS70 antibodies in different geographic areas using a standardized assay. Our findings show that the antibodies are most prevalent in young females.