Circulating immunoglobulin-secreting cells in rheumatoid arthritis.

The level of circulating cells secreting IgG, IgM, and IgA (IgSC) provides insight into the degree of in vivo polyclonal B-cell activation (PBA). Patients with rheumatoid arthritis (RA) exhibit abnormalities in humoral immune responses suggestive of augmented in vivo polyclonal B-cell activation. Therefore, a protein A reverse hemolytic plaque assay was used to measure the level of circulating IgSC in 32 RA patients. The mean level of circulating IgSC in RA patients was 3602 +/- 747 (SEM) compared to a mean of 1407 +/- 443 in patients with other types of arthritis and 1253 +/- 216 (P less than 0.02) in healthy volunteers. Levels found in RA patients did not appear to reflect disease activity or concomitant corticosteroid therapy. However, a subset of RA patients receiving gold therapy had levels of IgSC (1381 +/- 501) similar to those seen in healthy volunteers (P greater than 0.5). These data are consistent with augmented in vivo polyclonal B-cell activation in RA. In addition they suggest that gold affects mechanisms controlling in vivo B-cell activation.