Apical membrane receptors on intestinal M cells: potential targets for vaccine delivery.

Apical membrane-located receptors on intestinal Peyer's patch M cells have been identified as pathogen binding sites which have potential as targets for the delivery of formulated subunit and recombinant vaccine antigens. Gene expression studies have correlated outputs from a series of models including human intestinal M-like cell cultures and human Peyer's patch tissue. Outputs comprise novel receptors with unknown function and also conserved binding sites for an ever-increasing list of pathogens. Screening for ligands to mimic pathways used by selected pathogens for invading the human intestine has the potential for increasing the efficiency of delivery of oral vaccine antigens to M cells and consequently to sub-epithelial sites for antigen processing. Synthesis of efficient and specific targeting ligands to human M cells may eventually lead to formulations based on the formats of targeted antigen-loaded nanoparticles or ligand-conjugated stable antigens.