Increased numbers of active B cells in the circulation of patients with rheumatoid arthritis.

Increased numbers of cells secreting immunoglobulins of class G, M and A have been demonstrated in the peripheral blood of patients with active rheumatoid arthritis using the reverse haemolytic plaque assay. Lower numbers of secreting cells were detected in rheumatoid patients in spontaneous remission. Culture of the peripheral blood mononuclear cells was associated with a fall in the number of immunoglobulin secreting cells. Values for rheumatoid and normal cells did no differ significantly after 3 days of culture. The presence of an activating factor in th rheumatoid patients is postulated.