Expression of CD 21, CD 22, and the mouse erythrocyte receptor on peripheral B lymphocytes in rheumatoid arthritis.

The expression of the B cell antigens, CD 21, CD 22, and the mouse erythrocyte receptor (MER), on peripheral mononuclear cells (PMC) in 61 patients with rheumatoid arthritis (RA) and in 25 patients with various other forms of rheumatic disease was studied. Patients with RA showed significantly more peripheral B cells than control patients, whereas there was no difference between patients with RA and controls in resting B cells expressing the MER or resting and activated B cells expressing CD 21. Patients with active RA had significantly less MER positive and more CD 21 positive B cells than patients with inactive disease. The relation between disease activity and expression of MER and CD 21 was independent of drug treatment or production of classical rheumatoid factor. These data may be interpreted as a sign of B cell activation in RA. In addition, patients with seronegative RA receiving gold treatment showed significantly more MER positive cells than patients receiving different drugs, whereas patients receiving non-steroidal anti-inflammatory drugs (NSAIDs) alone had significantly more CD 21 positive cells. This may be the result of different immunomodulating effects of drugs on B cell subsets.