Capsaicin induces the production of IL-4 but not TNF-α in P815 cells. Cells were treated with different concentrations of capsaicin (C) for 3 hours. Solvent (Base) or 100 nmol/L PMA-treated cells were used as controls. The inhibitory effect of capsazepine (CPZ) was assessed by incubating one group of cells with 10 μmol/L CPZ in the presence of 10 μmol/L capsaicin. Supernatants were then collected and the produced TNF-α (A) or IL-4 (B) content was determined in duplicates by ELISA kits according to the manufacturer's protocol. Each of the measured doses of capsaicin caused significant release of IL-4 (*P < .01). CPZ significantly (**P < .05) decreased the release of IL-4 by capsaicin, whereas it did not modify the release (***P > .5) when applied alone (Student'st-test). Points represent mean values of three individual experiments; error bars indicate SEM.