Medical Wikipedia : The Medical Encyclopedia
Microfold Cells
Microfold Cells or M Cells are present in follicle-associated epithelium (FAE)
Follicle -associated epithelium is a specialized epithelium present over Peyer’s patch in small intestine and isolated lymphoid follicles.
M cells are seen in epithelial cells of the mucosa-associated lymphoid tissues.
Microfold Cells or M Cells
Where the M Cells present?
Microfold Cells or M Cells are present in follicle-associated epithelium (FAE)
Follicle -associated epithelium is a specialized epithelium present over Peyer’s patch in small intestine and isolated lymphoid follicles.
M cells are seen in epithelial cells of the mucosa-associated lymphoid tissues.
Microfold cells (or M cells) are found in the gut-associated lymphoid tissue (GALT) of the Peyer's patches in the small intestine, and in the mucosa-associated lymphoid tissue (MALT) of other parts of the gastrointestinal tract.
| Microfold cells (or M cells) are found | |||
|---|---|---|---|
| 1 | GALT - Gut-associated lymphoid tissue | Peyer's patches in the small intestine | |
| 2 | MALT - Mucosa-associated lymphoid tissue | Other parts of the gastrointestinal tract. | |
What are the antigen-presenting cells?
| Antigen-presenting cells | ||
|---|---|---|
| 1 | B lymphocytes | |
| 2 | Dendritic cells |
What is function of the M Cells?
M cells helps to transport antigens from intestinal lumen to immune system cells, and starts
an immune response or tolerance.
M cells function are phagocytosis and transcytosis. M cells are capable of taking up large particulate antigens from the lumen and transporting them intact into the subepithelial space.
| Function of the M Cells | ||
|---|---|---|
| 1 | Selective endocytosis of antigens from gut lumen | |
| 2 | Transport of microbes and antigens to intraepithelial macrophages and lymphocytes | |
| 3 | Macrophages and lymphocytes migrate to lymph nodes to start immune response |
How the M Cells take up antigens from lumen and delivered to antigen-presenting cells?
| M Cells mechanism to take up antigens | ||
|---|---|---|
| 1 | Endocytosis | |
| 2 | Phagocytosis | |
| 3 | Transcytosis |
Which pathogens exploit M Cells ?
| Mechanism of exploiting M Cells | Organisms | ||
|---|---|---|---|
| To penetrate intestinal epithelium | Shigella flexneri | ||
| 1 | Salmonella typhimurium | ||
| Yersinia pseudotuberculosis | |||
| Prions- bovine spongiform encephalitis (Mad-cow disease) | |||
| 2 | Exploitation as a virulence factor | EPEC -Pathogenic Escherichia coli | |
| 3 | For Dissemination | Polio and Reovirus |
How polio virus exploits M Cells for dissemination?
M cells express lectin-like molecules in the apical surface. These molecules help to promote binding to poliovirus and helps in dissemination.
What is the mechanism where M cells involved with IgA response in payer patches?
Antigens that bind to the M cell and are transported to the underlying Peyer patches generally elicit a positive (IgA) response.
M cell helps to connect Peyer patches and lymphoid follicles as conduit.
Once antigens enter the Peyer patch, TGF-β-secreting T cells promote B cell isotype switching to IgA.
If Peyer patch B cells are absent then M cells are also absent. [M cells have not seen in B cell–deficient animals, which lack Peyer patches]
Peyer patches have T cell-dependent areas and B cell-dependent/germinal centers typical of lymph nodes, but only efferent lymphatics.