Microfold cells (M cells)

Definition

Microfold cells, commonly referred to as M cells, are specialized epithelial cells found in the mucosal surfaces of the gastrointestinal tract, particularly in Peyer's patches. They play a critical role in the immune response by facilitating the transport of antigens from the gut lumen to underlying immune cells, thus acting as a bridge between the intestinal lumen and the immune system.

5 Must Know Facts For Your Next Test

1. M cells are characterized by their unique morphology, which includes a folding structure that allows them to efficiently capture and transport antigens.
2. These cells are strategically located above lymphoid follicles, making them ideally positioned to deliver antigens to dendritic cells and other immune cells in Peyer's patches.
3. M cells facilitate transcytosis, a process where they engulf antigens from the gut lumen and transport them across their cell body to present them to underlying immune cells.
4. In addition to their role in antigen transport, M cells can also contribute to mucosal tolerance by interacting with commensal bacteria and preventing unnecessary immune responses.
5. The dysfunction or loss of M cell activity can lead to impaired immune responses and increased susceptibility to intestinal infections.

Review Questions

• How do M cells contribute to the immune response in the gut?
  • M cells contribute to the immune response by capturing antigens from the intestinal lumen and transporting them to underlying immune cells, particularly dendritic cells in Peyer's patches. This process enhances the ability of the immune system to recognize and respond to pathogens. By bridging the gap between the gut environment and the immune system, M cells play a vital role in initiating appropriate immune reactions.
• What is the significance of M cell dysfunction in relation to gut immunity?
  • M cell dysfunction can significantly impair gut immunity by hindering antigen transport and presentation. This can lead to an inadequate immune response against pathogens and increased susceptibility to infections. Additionally, improper functioning of M cells may disrupt mucosal tolerance, potentially resulting in inappropriate immune reactions against commensal organisms or food antigens, contributing to conditions like inflammatory bowel disease.
• Evaluate how M cells interact with both pathogens and commensal bacteria within the gut environment.
  • M cells play a dual role in interacting with both pathogens and commensal bacteria in the gut. They efficiently capture pathogenic antigens for immune response activation while also engaging with commensal microbes to promote tolerance and maintain homeostasis. This delicate balance is crucial for preventing excessive inflammatory responses while ensuring effective immunity against harmful invaders. The ability of M cells to manage these interactions is key for sustaining gut health and preventing diseases associated with dysregulation of gut immunity.

Related terms

Peyer's patches:

Aggregates of lymphoid tissue located in the small intestine that play a crucial role in the immune surveillance of intestinal bacteria and generating immune responses.

Antigen-presenting cells (APCs): Cells that capture and present antigens to T cells, including dendritic cells, macrophages, and B cells, which are vital for initiating immune responses.

Mucosal immunity: A specialized immune response that protects mucosal surfaces, such as those in the gastrointestinal, respiratory, and urogenital tracts, from pathogens and maintains homeostasis.