Reaction of antibodies to rheumatoid arthritis nuclear antigen with a synthetic peptide corresponding to part of Epstein-Barr nuclear antigen 1.

Antibodies to rheumatoid arthritis nuclear antigen (RANA) are detected by immunodiffusion (ID) and immunofluorescence (IF), though reports of the identity of the antigen(s) have been conflicting. In this study it is shown conclusively that ID and IF anti-RANA react with epitopes on Epstein-Barr nuclear antigen 1 (EBNA-1) and that the major epitope detected by immunofluorescence is represented by a synthetic peptide, P62, corresponding to part of EBNA-1. In an enzyme linked immunosorbent assay (ELISA) anti-P62 antibodies in 35 rheumatoid arthritis sera were threefold higher than those of 35 age and sex matched controls, with the highest levels occurring in young patients with active joint disease.