Identification of the Site of Uptake of the E. coli Heat‐labile Enterotoxin, LTB

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Abstract
The results of this study demonstrate that the B subunit of the E. coli heat labile toxin (LTB) binds to the brush border of intestinal epithelial cells in a highly specific, lectin‐like manner. Uptake of LTB and transcytosis to the basolateral side of the enterocytes can be observed within 1 h after feeding, and occurs through both the villous epithelial cells and the epithelial cells overlying lymphoid follicles and Peyer's patches. Binding and uptake most probably occur via receptor‐mediated endocytosis, with GM1 ganglioside and galactoproteins on the enterocyte cell surface acting as specific ligands to which the LTB binds. Cell EL1SA data, together with the observed distribution of immunocompetent cells and the localization of LTB binding, suggest that LTB which is taken up by the villous enterocytes enters the circulation and subsequently generates an IgG immune response in the spleen. At the same time. LTB which is taken up via the patch associated epithelium generates a local IgG and IgA immune response within the Peyer's patches and intestinal lymphoid follicles.