Effect of drug therapy on circulating and synovial fluid Ig-secreting cells in rheumatoid arthritis

A common immunological abnormality in rheumatoid arthritis (RA) is an increased spontaneous polyclonal B cell activation. In order to study the influence of drug therapy in RA on the functional activity of B cells we enumerated spontaneous plaque-forming cells (PFC) in peripheral blood lymphocytes (PBL) and synovial fluid lymphocytes (SFL) by a reverse haemolytic plaque assay. Spontaneous IgG-, IgM-, and IgA-PFC in PBL of 26 patients with classical erosive RA receiving either gold salts or D-penicillamine were similar to those observed in 20 healthy controls. In contrast, significantly higher numbers of IgG- and IgA-PFC, but not IgM-PFC, were found in PBL of nine patients with classical erosive RA receiving non-steroidal anti-inflammatory drugs (NSAID) alone. Furthermore, spontaneous PFC in SFL from 16 consecutive patients with RA receiving second-line drugs, as well as 17 patients with other forms of arthritis (non-RA) were generally low and significantly less than those observed in 20 RA patients on NSAID alone. Moreover, a wide individual variation in PFC, especially in relation to the IgG class, was recorded in the synovial lymphocytes. These studies imply that treatment with second-line drugs is associated with normalisation of B cell activity in RA patients, and that the effect can be detected at the cellular level both in blood and synovial fluid.