Interleukin-1 (IL-1) can induce intestinal epithelial cells (IEC) to produce several cytokines and acute phase proteins, suggesting that IEC may be important in a cytokine network at the intestinal mucosa to amplify the effects of IL-1 during an inflammatory response. However, little is known about the type of IL-1 receptor expressed by IEC and the effect of cytokines on the expression of these receptors. In this study, the expression by IEC of IL-1 receptor Type I (IL-1RI) and type II (IL-1RII) mRNA was examined by reverse transcriptase polymerase chain reaction. Both isolated rat IEC and the rat IEC-6 intestinal epithelial cell line were found to express mRNA for IL-1RI but not IL-1RII. Stimulation of the IEC-6 cells with IL-1beta or TNF-alpha down-regulated the expression of mRNA for IL-1RI at 24 hr, yet transforming growth factor-beta1 was found to have no effect. These results suggest a possible mechanism to limit the effect of IL-1 on IEC function during the mucosal inflammatory response by down-regulating the expression of the Type I IL-1 receptor.