Intestinal M cells and their role in bacterial infection.

M cells are located in the epithelia overlying mucosa-associated lymphoid tissues such as Peyer's patches where they function as the antigen sampling cells of the mucosal immune system. Paradoxically, some pathogens exploit M cells as a route of invasion. Here we review our current knowledge of intestinal M cells with particular emphasis on the mechanisms underlying bacterial infection of these atypical epithelial cells.