Microfold cells

Definition

Microfold cells, or M cells, are specialized epithelial cells found in the mucosal surfaces of the gastrointestinal tract that play a key role in the immune response by transporting antigens from the lumen to immune cells. These cells facilitate the initiation of mucosal immunity by sampling and presenting antigens to underlying immune cells, thereby helping to maintain the balance between tolerance and activation in the gut.

5 Must Know Facts For Your Next Test

1. M cells are strategically located over Peyer's patches and other lymphoid tissues, allowing them to efficiently transport antigens to immune cells like dendritic cells and T cells.
2. Unlike other epithelial cells, M cells have a thinner glycocalyx and fewer microvilli, which enables easier access for antigens to be taken up from the intestinal lumen.
3. The interaction of M cells with pathogens can lead to a rapid immune response, making them essential for early detection of infections in the gut.
4. M cells also play a role in maintaining tolerance to non-harmful antigens like food proteins and commensal bacteria, preventing unnecessary inflammatory responses.
5. The dysfunction or loss of M cell function can contribute to gastrointestinal diseases such as inflammatory bowel disease (IBD) or increased susceptibility to infections.

Review Questions

• How do microfold cells facilitate the initiation of mucosal immunity?
  • Microfold cells facilitate mucosal immunity by capturing antigens from the intestinal lumen and transporting them across the epithelial barrier to underlying immune cells. This process allows for the direct interaction between antigens and immune cells such as dendritic cells, which can then activate T cells and other components of the immune system. By sampling these antigens, M cells play a crucial role in determining whether an immune response is needed or if tolerance should be maintained.
• Discuss the structural features of microfold cells that enable their function in antigen transport.
  • Microfold cells possess unique structural features that enhance their ability to transport antigens. They have a lower density of microvilli compared to typical epithelial cells, allowing for easier access to luminal antigens. Additionally, their thinner glycocalyx provides less resistance during antigen uptake. These adaptations make M cells particularly effective at sampling and delivering antigens to underlying immune tissues, such as Peyer's patches.
• Evaluate the implications of impaired microfold cell function on gut health and immunity.
  • Impaired function of microfold cells can significantly affect gut health and immunity by disrupting the balance between tolerance and activation. When M cells fail to sample antigens properly, it can lead to an increased risk of infections due to inadequate immune responses. Conversely, dysfunction may also result in inappropriate inflammatory responses to harmless antigens like food or commensal bacteria, contributing to conditions such as inflammatory bowel disease (IBD). Understanding these implications highlights the importance of M cell function in maintaining gut homeostasis.

Related terms

Peyer’s patches: Aggregates of lymphoid tissue located in the small intestine, containing M cells and playing a crucial role in the immune surveillance of intestinal bacteria and antigens.

dendritic cells: Antigen-presenting immune cells that capture, process, and present antigens to T cells, playing a vital role in initiating and shaping immune responses.

intestinal microbiota: The diverse community of microorganisms residing in the gastrointestinal tract, which interact with the host's immune system and contribute to maintaining gut health.