Primary Sjögren's syndrome and primary biliary cirrhosis: differences and similarities in the autoantibody profile

Sera from 61 patients with primary biliary cirrhosis (PBC) and 23 patients with primary Sjögren's syndrome (pSS) were tested for the presence of autoantibodies to 15 different antigens (PDH, RNP, SS-A, SS-B, Sm, Scl-70, H2AH2B, Jo-1, collagen-type I, GBM, GM <--> 1, Sulf, GD1b, MPO, PR3). Patients with pSS had significantly (p < 0.01) higher frequencies of antibodies to SS-A, SS-B and RNP (78%, 52%, 22% vs 29%, 20%, 5%, respectively) when compared to patients with PBC. On the other hand, patients with PBC had significantly (p < 0.01) higher frequencies of antibodies to PDH, Sm, Jo-1, collagen and MPO (80%, 34%, 26%, 52%, 67% vs 13%, 9%, 13%, 13%, 9%, respectively) as compared with patients with pSS. For all the other autoantibodies, no significant differences were found between PBS and pSS patients. These data on the similarities in autoimmunity between two diseases with different clinical presentations shed more light on the mosaic of autoimmunity.