Identification and characterization of the rat intestinal epithelial cell (IEC-18) interleukin-1 receptor

Interleukin-1 (IL-1), an important mediator of inflammation, may act in chronic inflammatory disorders of the intestine such as idiopathic inflammatory bowel diseases. Although the IL-1 receptor (IL-1R) has been studied extensively in many cell lines, including T cells, B cells, and fibroblasts, it has not been demonstrated on intestinal epithelial cells. IL-1 affects intestinal epithelial cell proliferation in vitro, suggesting the presence of IL-1Rs on intestinal epithelium. This paper demonstrates and further characterizes an IL-1R in a rat intestinal epithelial cell. Cells from rat intestinal epithelial cell line IEC-18 were grown to confluence in six-well plates, and association studies with 125I-labeled IL-1 beta to determine specific binding and equilibrium conditions were performed. A competitive-inhibition curve verified the IL-1 concentration required to saturate the IL-1R, and a Scatchard plot revealed a dissociation constant (Kd) of 1.2 x 10(-10) M, with 1,000 receptors per epithelial cell. Binding studies using increasing concentrations of 125I IL-1 beta alone confirmed the receptor density. Cross-linking 125I-IL-1 beta to the IEC-18 IL-1R demonstrated an IL-1R of approximately 80.5 kDa. cDNA transcribed from IEC-18 mRNA was used as a template for amplification of a segment of the IL-1R using complementary oligonucleotides. The resulting sequence of the IL-1R demonstrated a high degree of homology with both the human and mouse type I IL-1R.(ABSTRACT TRUNCATED AT 250 WORDS)