Objective: We investigated the in vitro immunomodulatory effects of sulfasalazine on B cells in rheumatoid arthritis (RA).
Methods: Reversed hemolytic plaque assay and 3H-thymidine incorporation were measured.
Results: B cells from patients with RA showed hyperactivity to stimulation by Staphylococcus aureus Cowan I. Sulfasalazine significantly inhibited this B cell hyperactivity in a dose dependent manner. The kinetic study and a decrease in 3H-thymidine incorporation on Day 3 indicate that sulfasalazine inhibited the early phase (0-48 h) of B cell proliferation in these patients. Sulfapyridine also inhibited B cell hyperactivity in these patients, but 5-aminosalicylic acid and N-acetylsulfapyridin had no significant effect.
Conclusion: Sulfasalazine exhibited a direct immunosuppressive effect on B cell hyperactivity in patients with RA, which may be responsible for its therapeutic effectiveness in this disorder.