Pathological effects of Phaseolus vulgaris isolectins on pig jejunal mucosa in organ culture.

The interaction of plant lectins with pig small intestinal epithelium in organ culture was studied. The binding of Phaseolus vulgaris (PHA) isolectins E4 and L4 to the microvilli and microvillus vesicles in the top area of the villi was shown by immunoelectron microscopy. Differences were observed in the distribution of the isolectins. In the explants cultured for five hours with the PHA isolectins, the enterocyte height and the villus length were decreased, and a lower villus: crypt ratio was calculated. Ultrastructurally, the microvilli were shorter and irregularly positioned. After incubation with both PHA E4 and PHA L4, clusters of small vesicles, tied off from the microvilli, were seen in higher numbers when compared with control explants. The activity of the brush border enzyme sucrase-isomaltase was reduced in the PHA E4 incubated explants but did not change in the PHA L4 incubated explants. This investigation shows that explants of pig jejunal mucosa in organ culture are suitable for study of the pathological effects of lectins on the small intestinal mucosa. This method may also be used in elucidating the mechanisms by which damage to mucosal structure occurs.