The production of interleukin-6, intracellular adhesion molecule 1, and major histocompatibility complex class II molecules by a renal carcinoma cell line (ACHN) in response to S fimbriae of uropathogenic Escherichia coli was studied. S fimbriae adhered to ACHN cells and stimulated the production of interleukin-6 and intercellular adhesion molecule 1 but did not affect major histocompatibility complex class II expression by renal carcinoma cells. Our data demonstrate that S fimbriae of E. coli display immunomodulating properties on kidney-derived epithelial cells.