Demonstration of high prevalence of SS-A antibodies in a general population: association with HLA-DR and enterovirus antibodies.

Autoantibodies are helpful markers for diagnosing autoimmune diseases and there is a link between HLA-DR3 and the prevalence of SS-A antibodies in clinical groups. We aimed to study this association at the level of general adult population and to verify whether these antibodies are more common in persons with antibodies against enteroviruses as possible associates of Sjögren syndrome. The studied material included sera from 200 persons, randomly selected from a general population sample. The IgG type of SS-A/SS-B autoantibodies were measured by nuclear immunoblot, developed by us, and the results were compared to other results obtained by anti-SS-A immunoblot and ELISA. Enterovirus antibodies were detected by ELISA using common enterovirus antigenic peptide KEVPALTAVETGAT. Altogether 33 out of 200 sera showed SS-A and/or SS-B bands in immunoblot, including all seven ANA Profile 3 (Euroimmune) positive sera. One of the persons positive in these two tests showed also positive reaction on anti-SS-A ELISA (Euroimmune). None of the antibody-positive persons had Sjögren's syndrome or other rheumatic disease. Among 82 HLA typed persons, selected at random, the HLA-DRB1*03 and HLA-DRB1*11 allele carriers included significantly more persons with SS-A antibodies than the non-carries (p = 0.008). Antibodies against enterovirus peptide were present more frequently in persons with SS-A autoantibodies than in age- and sex-matched controls (p = 0.009). Summing up, our study showed that the prevalence of SS-A/SS-B antibodies in a general random population might be higher than thought previously being detected in up to 16.5% of persons including a significant number of those with HLA-DR3 or/and DR11 alleles and with antibodies against enteroviruses. Whether all these persons have the risk of developing rheumatic diseases should be evaluated by follow up studies.