Non-Conventional and Emerging Autoantibodies in Sjögren's Disease

Sjögren's disease (SjD) is a chronic autoimmune disease that is characterised by dryness symptoms, arthralgias, systemic disease and B-cell hyperactivity. Serum autoantibodies are key pathological features of this disease. Anti-Ro52, anti-Ro60 and anti-La immunoglobulin G autoantibodies (sometimes known as antinuclear antibodies) are perhaps the most well-known autoantibodies, are important in the formal classification criteria for SjD and exist in up to 70% of patients. Rheumatoid factors, which are present in approximately 50% of patients, can reveal important prognostic information regarding the development of B-cell lymphomas. Beyond these autoantibodies, there are several emerging and novel autoantibodies associated with SjD that hold promise in identifying clinical features of SjD and facilitating the diagnosis of patients who lack the classic SjD-associated autoantibodies. These include anti-fodrin antibodies, anti-muscarinic acetylcholine receptor 3 antibodies and those autoantibodies traditionally associated with systemic lupus erythematosus. This narrative review article provides an updated review of these autoantibodies, discussing their potential clinical utility and the current limitations. Although many clinical associations have been identified, the routine clinical use of these autoantibodies is hampered by issues such as poor diagnostic sensitivity, contradictory associations, heterogeneous studies and small single-cohort studies. Further research using harmonised testing and large, multicentre cohorts is required to explore and validate the utility of these autoantibodies.