Differential binding of lectins to M cells and enterocytes in the rabbit cecum.

BACKGROUND

The afferent limb of the intestinal immune system is represented by the gut-associated lymphoid tissue, in which antigenic material, including complete bacteria, is taken up from the lumen by specialized epithelial cells (M cells). Because the adherence of micro-organisms to epithelial can be mediated by lectin-sugar bindings, the glycoconjugates of the surfaces of M cells and enterocytes were compared.

METHODS

A set of 28 lectins and corresponding sugars was used for light and electron microscopy of fixed and unfixed sections. M cells were identified by anti-vimentin antibodies.

RESULTS

M cells of the cecal lymphoid patches selectively bound lectins specific for fucose or N-acetylgalactosamine. The labeled glycoconjugates were located in the apical membrane and in the membrane of vesicles in the apical cytoplasm. Enterocytes were selectively labeled by galactose-specific lectins. In contrast, the lectin-reactivity of M cells and enterocytes did not differ in the jejunal Peyer's patches.

CONCLUSIONS

The results suggest that there may be selectivity mediated by glycoconjugates in the uptake of antigenic material by cecal M cells but not by jejunal M cells.