Gut, Immune organ-mucosal immunity of gastro-intestinal tract-

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Background and Objective : To clarify a role of the gastrointestinal tract in mediating immunity, we examined following three points between 1995 and 1996, using experiments where gastrointestinal epithelial cells are infected by bacteria and viruses. (1) Whether mRNA of the chemokine family is expressed in epithelial cells, (2) whether the chemokine mRNAs are translated into proteins and (3) whether the chemokine proteins have any functions. As a result, the patterns of chemokines produced by gastrointestinal epithelial cells due to bacterial or viral infections differed from each other, which was thought to be the main cause of the diversity in local mobilization of inflammatory cells and inflammatory responses against various infections. Furthermore, IL-8 obtained from supernatant of cell culture was concentrated, then added to neutrophils and briefly cultured. Subsequently, expression levels of CD11b/18 and Leu8 (L-selectin) on the surface of neutrophils were measured by FACS,resul … More ting in an increase in CD11b/18 and a decrease in L-selection expression. And anti-IL-8 antibody partially inhibited these increases and decreases, suggesting that IL-8 in supernatant of cell culture plays a role in activating neutrophils. However, other cytokines are also involved.Then in 1997, we used an Ussing chamber to electrophysiologically analyze the influence of various chemokines and supernatant of cell culture on T84 and/or 18CO (human gastrointestinal fibroblasts) and/or neutrophils coculture systems. In addition, establishment of a mast cell line was attempted, to examine the effects of mast cells instead of neutrophils.Methods and Results : Coculture of gastrointestinal epithelial cells with fibroblasts facilitated membrane depolarization, and coculture with neutrophils further facilitated depolarization. A mast cell line was established using a culture system where IL-6, stem cell factor and prostaglandin E_2 were added to mononuclear cells from cord blood. We intend to further investigate the coculture system with this cell lone. Less