The polymeric immunoglobulin receptor (secretory component) in a human intestinal epithelial cell line is up-regulated by interleukin-1.

Abstract

Secretory component (SC or polymeric immunoglobulin receptor) on mucosal epithelial cells mediates transcytosis of polymeric immunoglobulin into external fluids and functions as a receptor for polymeric immunoglobulin. SC expression in a human colonic adenocarcinoma cell line, HT-29 has been reported to be up-regulated by various cytokines, such as interferon-gamma, tumour necrosis factor-alpha and interleukin-4 (IL-4). However, up-regulation of SC by IL-1 is controversial. In this study, we investigated the effect of human recombinant IL-1 alone on SC expression in HT-29 cells in detail. Immunocytochemistry and Northern blot analysis revealed that IL-1 beta increased both the number of SC-positive cells and SC mRNA expression. Enzyme-linked immunosorbent assay revealed that IL-1 beta enhanced secretion by HT-29 cells in both time- and dose-dependent manners. IL-1 alpha had the same effects on HT-29 cells. Northern blot analysis demonstrated that cycloheximide and actinomycin D abolished the effect of IL-1. Moreover, we detected IL-1 receptor (IL-1R) type I mRNA in HT-29 cells by polymerase chain reaction (PCR) and sequenced the PCR-amplified product. We think that it reflects the possibility of the presence of IL-1R in HT-29 cells. From these data, we concluded that IL-1 beta and IL-1 alpha play regulatory roles in SC expression, and their effects depend on de novo protein synthesis and transcription.