Connective tissue diseases (CTD) – rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjögren syndrome (SS), systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIM), mixed connective tissue disease (MCTD) – are a heterogeneous group of systemic autoimmune disorders. Like other autoimmune diseases CTD are characterized by the production of autoantibodies that can be detected in patients’ sera. Most of the time, autoantibodies are used as diagnostic markers of CTD. Whether or not autoantibodies are involved in CTD pathogenesis is still debated.
