Analysis of antibody titers to Epstein-Barr virus nuclear antigens in sera of patients with Sjögren's syndrome and with rheumatoid arthritis.

To examine if Epstein-Barr virus (EBV) infection is associated with the two autoimmune diseases, Sjögren's syndrome and rheumatoid arthritis, IgG antibody titers of sera from patients with the disorders were evaluated for five constituents of EBV nuclear antigens (EBNA-1, -2, -3, -4, and -6). To circumvent interference by autoantibodies in the sera, fusion proteins synthesized in Escherichia coli were used as specific antigens. By ELISA the average IgG antibody titers to domains of the five EBNAs, especially the amino-terminal domain of EBNA-2, in sera of patients with Sjögren's syndrome were slightly higher than those in normal sera. The tendency of sera from Sjögren's syndrome patients to have higher reactivities to the EBNA domains was also observed by immunoblotting. By comparison, few heightened serologic responses to EBNAs were observed in sera from patients with rheumatoid arthritis. Further analyses are required to determine if EBV is associated with Sjögren's syndrome in any way.