ALTERED IMMUNE-RESPONSE TO GLYCINE-RICH SEQUENCES OF EPSTEIN-BARR NUCLEAR ANTIGEN-1 IN PATIENTS WITH RHEUMATOID-ARTHRITIS AND SYSTEMIC LUPUS-ERYTHEMATOSUS

Prior studies have shown that patients with rheumatoid arthritis (RA) have an increased number of circulating Epstein‐Barr virus–infected B lymphocytes and elevated titers of antibody to Epstein‐Barr nuclear antigen–1 (EBNA‐1), the major nuclear antigen expressed in latently infected B cells. However, it is not known whether antibodies from RA patients recognize the same epitopes as antibodies from normal subjects. Most of the anti–EBNA‐1 antibodies in normal subjects are directed at the glycine‐alanine repeating region of the molecule. Antibodies specific for this region are also somewhat more prevalent in RA patients than in normal subjects. A panel of synthetic peptides derived from EBNA‐1 was used to analyze the immune response to antigenic epitopes outside the glycine‐alanine region, using the peptides as solid‐phase antigen. Sera from RA patients and from systemic lupus erythematosus patients contained elevated levels of IgG antibodies to 2 non–glycine‐alanine peptides and to 3 non–glycine‐alanine peptides, respectively. Two of the 3 peptides are glycinerich, but antibodies that react with them are distinct from each other, as well as from those that react with the glycine‐alanine epitope. Eight other peptides from the C‐terminal portion of EBNA‐1 either do not react with sera or show no difference between normal subjects and patient groups. The antibodies to the glycine‐alanine peptide are enriched with k light chains, whereas antibodies to epitopes outside the glycinealanine region are not so restricted among k and λ light chains. Thus, RA patients and systemic lupus erythematosus patients have different antibody responses than do normal subjects, both quantitatively and qualitatively. Copyright © 1990 American College of Rheumatology