M cells

Definition

M cells, or microfold cells, are specialized epithelial cells found in the mucosal surfaces of the gut that play a key role in the immune response by transporting antigens from the intestinal lumen to underlying immune cells. They facilitate the uptake of pathogens and other foreign substances, promoting an effective immune response and maintaining gut homeostasis.

5 Must Know Facts For Your Next Test

1. M cells are primarily located over Peyer’s patches, which are lymphoid tissues essential for gut immunity.
2. These cells have a unique structure that allows them to transport large particles and microorganisms through their microfolds.
3. M cells play a vital role in sampling luminal antigens and delivering them to dendritic cells, which helps initiate immune responses.
4. They also help maintain a balance between tolerance and activation of immune responses, preventing unnecessary inflammation.
5. The function of M cells can be influenced by various factors, including microbiota composition and dietary components.

Review Questions

• How do M cells facilitate immune responses in the gut?
  • M cells facilitate immune responses by transporting antigens from the intestinal lumen directly to underlying immune cells like dendritic cells. This process allows for efficient sampling of pathogens and other foreign substances, helping initiate an appropriate immune response. By bridging the gap between the gut's external environment and the immune system, M cells play a critical role in maintaining gut homeostasis.
• Discuss the structural features of M cells that enable their unique function in antigen transport.
  • M cells have distinct structural features that set them apart from other epithelial cells. They possess microfolds, which increase their surface area for antigen uptake. Additionally, they lack the typical brush border found on absorptive epithelial cells, allowing for easier transport of larger particles. These adaptations enable M cells to effectively sample antigens from the gut lumen and deliver them to underlying immune cells, playing an essential role in initiating mucosal immune responses.
• Evaluate the implications of dysfunctional M cell activity on gut immunity and health.
  • Dysfunctional M cell activity can lead to impaired antigen transport and result in a weakened immune response in the gut. This dysfunction may cause an inability to recognize pathogens effectively, increasing susceptibility to infections and gastrointestinal diseases. Additionally, it could contribute to dysbiosis, where harmful bacteria proliferate due to inadequate immune surveillance. Overall, compromised M cell function may disrupt gut homeostasis, leading to systemic inflammatory conditions or autoimmune disorders.

Related terms

Dendritic Cells: Immune cells that capture and present antigens to T cells, playing a critical role in initiating and regulating immune responses.

Peyer’s Patches: Aggregated lymphoid follicles located in the intestinal mucosa, where M cells are found, and which contribute to the immune surveillance of the gut.

Goblet Cells: Epithelial cells that secrete mucus to protect and lubricate the intestinal lining, contributing to mucosal immunity.