REGIONAL DIFFERENCES IN GLYCOCONJUGATES OF INTESTINAL M-CELLS IN MICE- POTENTIAL TARGETS FOR MUCOSAL VACCINES

We have used a panel of lectins and antibodies to describe the composi tion of complex carbohydrates associated with M cells in various regio ns of the intestinal tract of adult BALB/c mice. The fucose-specific l ectin Ulex: europaeus agglutinin type I (UEA I) is a marker of M cells in the small intestine and recognized M cells at an early stage of di fferentiation. Subpopulations of M cells in a single follicle-associat ed epithelium (FAE) could be distinguished by different fucose-specifi c probes. Certain lectins revealed that M cells have basal processes t hat extend into the underlying lymphoid tissue. Colonic and rectal M c ells display glycosylation patterns distinct from M cells of Peyer's p atches and are characterized by terminal galactose. UEA I selectively adhered to Peyer's patch M cells in mucosal explants and in ligated in testinal loops in vivo. The lectin was taken up into endocytic vesicle s and transported to the intraepithelial pocket and other domains of t he basolateral membrane. Thus M cell-specific glycoconjugates could se rve as ''receptors'' for targeting of lectin-antigen conjugates to the mucosal immune system.