In vitro immunoglobulin production by lymphocytes of patients with juvenile rheumatoid arthritis: effects of Staphylococcus aureus Cowan I stimulation and monocyte depletion.

Pokeweed mitogen (PWM) and Staphylococcus aureus Cowan I (SAC) were used to stimulate in vitro IgG and IgM production by lymphocytes of 27 patients with juvenile rheumatoid arthritis (JRA). Twelve had reduced stimulation indices for PWM stimulated cultures of T and non-T cells. Stimulation with SAC resulted in increased IgM production in half (5/10); and partial removal of monocytes resulted in improved PWM induced IgM production in 5/7. IgG production was less easily improved. The results of our study suggest that while PWM induced Ig production may be reduced, B cells responding to SAC may function normally in some patients with JRA. In others, monocyte mediated suppression may account for reduced responses to PWM.