Effect of Varying Types of Anti-Arthritic Drugs on TH1 and TH2 Immune Responses in Mice

The present study was undertaken to study the effect of varying types of anti-arthritic drugs on Th1 and Th2 immune responses in mice. To immunize mice, ovalbumin (OVA) emulsified with complete Freund's adjuvant was injected s.c. at the base of the tail (day 0). Indomethacin (IND) as a non-steroidal antiinflammatory drug (NSAID), dexamethasone (DEX) as a steroidal antiinflammatory drug, methotrexate (MTX), auranofin (AUR), and D-penicillamine (D-PA) as anti-rheumatic drugs were orally administrated daily from days 0 to 20. On day 21, anti-OVA IgG2a and interferon (IFN)-γ as indicators of Th1 responses and anti-OVA IgG1 and interleukin (IL) −10 as those of Th2 responses were measured. Treatments with IND, DEX, MTX and AUR were followed by decreases in OVA-specific IgG and proliferation of spleen cells to the antigen. Treatments with IND, DEX, MTX and AUR inhibited both Th1 and Th2 immune responses, although the inhibitory effects of these drugs on the antigen-specific IgG2a and IFN-7 production appeared to be greater than those on IgG1 and IL-10 production. D-PA failed to influence anti-OVA IgG, IgG2a and IgG1 production as well as IFN-γ and IL-10 secretion. Administrations of all the drugs used resulted in suppression of antigen (OVA)-induced arthritis in mice which was associated with inhibition of anti-OVA IgG2a but not IgG1 production. These results suggest that anti-arthritic drugs including IND, DEX, MTX and AUR appear to suppress Th1 and, to a lesser extent, Th2 immune responses, and their antiinflammatory effects on human rheumatoid arthritis might be at least in part explained by downregulation by these drugs of Th1 responses involved in the disease.