We describe a model to study the effects of polymorphonuclear leukocyte (PMN) transmigration on the intestinal epithelial barrier. Human PMN were induced to transmigrate across high resistance monolayers of a cultured human intestinal epithelial cell line (T84 cells) by chemotactic gradients produced by formyl methionyl leucyl phenylalanine (FMLP). With maximal transmigration monolayer resistance decreased by 48±12.6% in 15 min and by 83±1.6% in 60 min. This response was dependent on the size of the FMLP gradient and the density of PMN transmigration. The decrease in resistance correlated with number of PMN migrating across monolayers, and was accompanied by increases in flux of paracellular tracers. Macromolecular tracer studies localized the leak sites to foci at which PMN impaled the epithelium. Removal of the chemotactic gradient led to restoration of baseline resistance within 18 h. PMN transmigration across intestinal epithelial monolayers occurs via intercellular occluding junctions and may be associated with a reversible increase in epithelial permeability.

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A secreted product of activated neutrophils, NDS (neutrophilderived secretagogue), elicits a short circuit current (Isc) in epithelial monolayers derived from the human intestinal cell line T84 (J. Clin. Invest. 1991. 87:1474-1477. Here, we identify and characterize the source of this Isc and examine associated signaling pathways. 125I efflux studies suggested that NDS activates an anion conductive channel. Bidirectional 22Na MCI flux studies showed that electrogenic Cl-secretion fully accounts for the NDS-induced Isc response. NDS behaved in many respects as a cAMP-mediated secretagogue: NDS did not further increase maximal cAMP-induced Cl-secretion; NDS potentiated Ca2+-mediated Cl secretion; and NDS elicited measurable 1251 but not 1Rb effluxes. However, NDS did not elicit a detectable rise in intracellular cAMP. Such data suggest that NDS may elicit Cl-secretion by effecting distal events in the cAMP-mediated pathway. Data derived from cell volume assays of isolated guinea pig intestinal crypt cells indicated that NDS also directly elicits Cl-secretion from natural intestinal epithelia. Additionally, since NDS activity is released from PMN by stimuli normally present in the colonic lumen, since NDS is active when applied apically to this model intestinal epithelium, and since the NDS-elicited Isc response is indicative of electrogenic chloride secretion, we speculate NDS may contribute to the secretory diarrhea encountered in many patients with inflammatory intestinal disease. (J. Clin. Invest.

In order to model crypt abscesses, a histological finding which correlates with disease activity in intestinal inflammation, human polymorphonuclear leukocytes (PMN) were layered onto monolayers of the human intestinal epithelial cell line T84, a crypt-like epithelium which is capable of Cl-secretion. Such PMN-epithelial interaction had no substantial effect on monolayer integrity or function. However, when PMN were stimulated by conditions including those present naturally in the human colonic lumen, monolayers responded with a bumetanidesensitive short circuit current (Isc) indicative of Cl-secretion, the basis of secretory diarrhea. This Isc response was induced by a neutrophil-derived secretagogue (NDS), which was only active when applied to the luminal surface of monolayers and did not require PMN-epithelial contact. NDS activity is resistant to boiling, acid, and trypsin and passes a 500 nominal mol wt cutoff filter. NDS activity is not secondary to the respiratory burst products O-or H202 and does not appear to be a myeloperoxidase product. We speculate NDS elicited Cl-secretion may contribute to the secretory diarrhea seen in patients with intestinal inflammation and crypt abscesses. (J. Clin. Invest.

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