Inhibition of interleukin 5 production with no influence on interleukin 4 production by an anti-allergic drug, tranilast in Toxocara canis-infected mice

Tranilast is well-known as a useful drug for allergic diseases. This drug i s believed to exhibit its therapeutic effects by inhibiting the release of chemical mediators from mast cells and basophils. Effects of tranilast on T helper type 2 (Th2) cytokine production were investigated in mice infected with Toxocara canis (Tc). Tranilast reduced interleukin (IL)-5 production in a dose-dependent manner but not IL-4 production at all in lung and splee n cells from Tc-infected mice cultured under stimulation with excretory-sec retory antigen. Obvious IL-5 mRNA expression was observed at week 1 in the lung alone, and IL-4 mRNA expression was detected at similar levels at week s 1-6 of infection in both lung and spleen. IL-5 but not IL-4 mRNA expressi on in the lung was significantly inhibited by daily administration of 100 m g/kg of tranilast for 1 week. This treatment also reduced the serum IL-5 le vel. Thus, tranilast inhibited IL-5 but not IL-4 production either in vitro or in vivo. The results imply that IL-5 and IL-4 production by Th2 cells m ay be controlled through different mechanisms. (C) 2000 International Socie ty for Immunopharmacology. Published by Elsevier Science Ltd. All rights re served.