Background: The diagnosis of autoimmune diseases depends on clinical history, physical examination, and laboratory detection of specific autoantibodies directed against nuclear or cytoplasmic antigens. The aim of this study was to investigate the types and prevalence of serum ANA, anti-dsDNA, and anti-ENA antibodies in a population examined at the Immunology Laboratory of the Naval Hospital of Athens and their correlation with patient age and gender.
Methods: We evaluated the sera of 3000 patients, both male and female, aged between 18 and 75 years old, born in different parts of Greece. All requests for ANA detection were performed by enzyme linked immunoassay (ELI SA). All ELISA borderline, weak positive and positive results were run on the indirect immunofluorescence assay (IFA) on Hep-2 cells. Anti-dsDNA antibodies were detected by IFA on Crithidia luciliae substrate slides. Antibodies to Sm, RNP, SS-A(Ro), SS-B(La), Jo-1, and Scl-70 were determined by an immunodot qualitative test.
Results: 206 patients were positive for ANA, representing a prevalence of 6.87%. The positive samples demonstrated the expected variety of titers and reactivity patterns. 9 samples (4.37%) presented anti-dsDNA positive result and 44 (21.36%) presented reactivity to various ENA autoantibodies. All the examined autoantibodies presented a higher prevalence among women.
Conclusions: In this study we estimated the prevalence of ANA, anti-dsDNA, and anti-ENA antibodies in samples of 3000 sera. We followed the strategy of performing immunofluorescence testing in order to confirm positive ELISA results, proposed by many scientists. We also evaluated autoantibody titers and fluorescence patterns, and we examined the correlation of autoantibody presence with patient age and gender.