DIFFERENTIAL SECRETION OF INTERLEUKIN-8 BY HUMAN EPITHELIAL-CELL LINES UPON ENTRY OF VIRULENT OR NONVIRULENT YERSINIA-ENTEROCOLITICA

Epithelial cells of the intestinal mucosa are among the first cells en countered by invasive pathogens. Bacterial invasion of the mucosa give s rise to an inflammatory response, characterized by the influx of pol ymorphonuclear leukocytes. The chemotactic stimulus responsible for th is accumulation is unknown, but several in vitro studies have demonstr ated that epithelial cells secrete the chemokine interleukin-8 (IL-8), a potent chemoattractant of polymorphonuclear leukocytes, upon bacter ial entry. In this study we analyzed the secretion of IL-8 by human in testinal (T-84) and cervical (HeLa) epithelial cell lines in response to infection with the enteric pathogen Yersinia enterocolitica. IL-8 w as secreted by T-84 and HeLa cells in response to invasion by Y. enter ocolitica. Virulent Y. enterocolitica induced a significantly lower le vel of IL-8 secretion than nonvirulent Y. enterocolitica. Subsequent a nalysis employing a mutant defective in Yop secretion and various yop mutants showed that the reduced secretion of IL-8 is due to the presen ce of Yop proteins. Our data suggest that YopB and YopD are required f or the suppressive effect.