Abnormally elevated frequency of Epstein-Barr virus-infected B cells in the blood of patients with rheumatoid arthritis

Patients with rheumatoid arthritis (RA) are known to have in vitro regulatory T cell abnormalities relating to Epstein-Barr virus (EBV). In this report, we asked whether patients with RA have more circulating EBV-infected B cells than normals. To address this question, we determined the frequency of spontaneously transforming B cells in the peripheral blood of 18 normals, 15 patients with RA, and 8 patients with systemic lupus erythematosus (SLE). The mean frequency of spontaneously transforming B cells in RA patients was 10.1/10(6) B cells, which was significantly greater than that of the normal controls, 2.8/10(6) B cells (P less than 0.005). The group of patients with SLE did not differ from the normals (P greater than 0.4). In further studies undertaken to investigate as to whether RA B cells are more easily transformed by EBV than normal B cells, we determined that the frequencies of transforming B cells in the presence of exogenous EBV were similar in RA patients and normals. Lymphocytes obtained from patients with RA demonstrate a profound T cell defect in their EBV-specific suppression, as measured in vitro; there was no direct correlation, however, between this in vitro T cell abnormality and the number of circulating EBV-infected B cells. Thus, patients with RA, as a group, have abnormally elevated numbers of circulating EBV-infected B cells, and this abnormality most likely derives from a complex dysregulation of the defense mechanisms for infection with EBV.