Histochemical comparison of the epithelial mucins in the ileum in Crohn's disease and in normal controls.

A comparison of routine and special histochemical methods that were applied to the epithelial mucins of small intestine from patients with Crohn's disease and from normal controls showed that the normal small intestine (ileum) goblet cells secrete a predominantly non-sulphated sialomucin and that, in contradistinction to the colon, the neuraminidase insensitivity of the sialic acids of the small intestine was not due to either O-acylation at C4 or an ester substituent at C1. Presumably this implies that the protection against enzyme attack afforded to the mucosa by the mucin coat in the small intestine utilises a different mechanism from that in the colon and that, although in many respects the small intestinal mucins in Crohn's disease, and in normal controls are similar, there is an increase in side-chain O-acylated sialic acids in such mucins in Crohn's disease. This difference has not been described before, probably because it can be seen only after staining such sections by the PAT/KOH/PAS and the PBT/KOH/PAS techniques.