Microfold cell

Microfold cell
Latin	epitheliocytus microplicatus
Code	TH H3.04.03.0.00010

M cells (or microfold cells) are cells found in the follicle-associated epithelium of the Peyer's patch. They transport organisms and particles from the gut lumen to immune cells across the epithelial barrier, and thus are important in stimulating mucosal immunity.

Unlike their neighbouring cells, they have the unique ability to take up antigen from the lumen of the small intestine via endocytosis or phagocytosis, and then deliver it via transcytosis to dendritic cells (an antigen presenting cell) and lymphocytes (namely T cells) located in a unique pocket-like structure on their basolateral side.

Structure and function

M cells differ from normal enterocytes in that they lack microvilli on their apical surface, but instead possess broader microfolds that give the cell its name. These cells are also far less abundant than enterocytes. M cells are readily accessible for antigens in the gut lumen to travel through to the Peyer's patch because they do not secrete mucus or digestive enzymes and the filamentous brush border glycocalyx (an extracellular polysaccharide layer found throughout the intestine attached to enterocytes) is much thinner or absent on M cells.

Pathology

M cells are exploited by several pathogens, including Shigella flexneri, Salmonella typhimurium, and Yersinia pseudotuberculosis, as well as infectious prions in Bovine spongiform encephalitis (Mad-cow disease), as a way to penetrate the intestinal epithelium. EPEC containing plasmids with genes for EAF(E coli Adherence Factor)will adhere to M cells.

They are also exploited by viruses such as Polio and Reovirus for dissemination. ^[1]

CXCR4 tropic but not CCR5 tropic HIV has been noted to be able to bind to M cells and get transported across the epithelium by them.^[2]

Development

Factors promoting the differentiation of M cells have yet to be elucidated, but they are thought to develop in response to signals from immune cells found in the developing Peyer's patch.^[3]

References

1. ^ Laurent Ouzilou1, Elise Caliot2, Isabelle Pelletier1, Marie-Christine Prévost3, Eric Pringault2 and Florence Colbère-Garapin1. Journal of General Virology (2002), 83, 2177-2182.
2. ^ Grigorios Fotopoulos*, Alexandre Hararidagger , Pierre MichettiDagger , Didier Trono§, Giuseppe Pantaleodagger , and Jean-Pierre Kraehenbuhl. July 1, 2002, 10.1073/pnas.142586899
3. ^ Kraehenbuhl J, Neutra M (2000). "Epithelial M cells: differentiation and function.". Annu Rev Cell Dev Biol 16: 301–32. doi:10.1146/annurev.cellbio.16.1.301. PMID 11031239.  Link

External links

• Slide at ucsd.edu