ABSTRACT
We studied the suppressor cell activity induced by concanavalin A (Con A) in 9 patients with acute febrile juvenile rheumatoid arthritis (JRA). The suppressor activity of JRA patients was higher than that of normal controls. However, the activity was significantly reduced by treating Con A-activated cells with mitomycin C (MMC) (P less than 0.05). On the other hand, the suppressor activity of normal controls and systemic lupus erythematosus (SLE) patients was not affected by MMC treatment. Two of 5 SLE patients showed low activity even before MMC treatment. The addition of the culture supernatant of Con A-stimulated peripheral blood mononuclear cells from a normal donor restored the induction of suppressor activity of JRA which was decreased by MMC treatment. The results indicated that patients with acute febrile type of JRA had reduced MMC resistant suppressor cell activity and that this was due to a defect in the ability of the cells to produce soluble factors needed to induce MMC resistant suppressor cells.