ABSTRACT
The influence of Epstein-Barr virus (EBV) infection on clinical and serological features of rheumatoid arthritis (RA) were studied. Patients with in-vivo activated, in-vitro spontaneously proliferating EBV-infected B lymphocytes had higher levels of serum IgG and IgA, and tended to have more extensive disease. The finding of in-vivo activated EBV-transformed B cells was not specific for RA but was also seen in patients with ankylosing spondylitis. When supernatants of spontaneously proliferating B-cell lines from patients with RA were studied, autoantibody reactivities comparable with those from patients with infectious mononucleosis were detected. These observations suggest that EBV infection might have a profound influence on B-lymphocyte responses and clinical course in patients with RA.