Intestinal epithelial cells produce various inflammatory mediators. However, the way in which immunosuppressive agents influence the production of these mediators by intestinal epithelial cells is not understood. The effects of cyclosporine A (CsA), tacrolimus (FK506), and dexamethasone (DEX) on cytokine-induced production of interleukin (IL)-8 in a human colonic cancer cell line (HT-29) were examined. HT-29 cells were stimulated with either IL-1 beta or tumor necrosis factor alpha (TNF alpha) together with CsA, FK506, or DEX. The presence of IL-8 protein was detected by enzyme-linked immunosorbent assay, and the expression of IL-8 messenger RNA (mRNA) by reversetranscription polymerase chain reaction. CsA (1, 5, and 10ng/ml) significantly reduced IL-1 beta-induced IL-8 production (by 32%, 41%, and 48%, respectively), and reduced TNF alpha-induced IL-8 production (by 21%, 42%, and 50%, respectively). FK506 or DEX had no effect on IL-1 beta- or TNF alpha-induced IL-8 production. The expression of IL-8 mRNA was also inhibited by CsA. These findings suggest that CsA may influence the production of inflammatory mediators in colonic cells in a different manner from FK506 and DEX.