Dendritic cells

Definition

Dendritic cells are a type of immune cell that act as messengers between the innate and adaptive immune systems. They play a crucial role in capturing and presenting antigens to T cells, helping to initiate a targeted immune response against pathogens while also maintaining tolerance to self-antigens. Their strategic position in tissues and ability to migrate to lymph nodes make them essential for linking the microbiome and the immune system.

5 Must Know Facts For Your Next Test

1. Dendritic cells are found in tissues that are in contact with the external environment, such as the skin and mucosal surfaces, allowing them to effectively capture pathogens.
2. They have a unique ability to undergo maturation after antigen capture, transforming from a 'resting' state to an 'activated' state, which enhances their ability to stimulate T cells.
3. Dendritic cells can produce various cytokines that influence the type of immune response generated, such as promoting a Th1 or Th2 response depending on the pathogen.
4. In addition to their role in initiating adaptive immunity, dendritic cells also contribute to immune tolerance by presenting self-antigens, helping prevent autoimmunity.
5. Research shows that dendritic cells interact with the gut microbiome, influencing how the immune system responds to both beneficial and harmful microbes.

Review Questions

• How do dendritic cells facilitate communication between the innate and adaptive immune systems?
  • Dendritic cells act as key intermediaries by capturing antigens through phagocytosis or endocytosis in peripheral tissues. Once they process these antigens, they migrate to lymph nodes where they present the processed antigens on their surface to T cells. This presentation is crucial for T cell activation and helps bridge the innate responses with a specific adaptive immune response.
• What roles do dendritic cells play in maintaining immune tolerance while still protecting against pathogens?
  • Dendritic cells not only activate T cells against foreign antigens but also play a critical role in establishing immune tolerance. They can present self-antigens in a way that does not activate T cells, thereby preventing autoimmune reactions. By balancing activation and tolerance, dendritic cells ensure that the immune system can respond effectively to pathogens without overreacting to harmless self-components.
• Evaluate the impact of dendritic cell interactions with the gut microbiome on overall health.
  • The interactions between dendritic cells and the gut microbiome are vital for shaping immune responses and maintaining health. Dendritic cells sample microbial antigens and communicate with other immune cells to either promote tolerance toward beneficial microbes or mount a defense against harmful pathogens. This dynamic relationship helps maintain gut homeostasis and has implications for conditions like inflammatory bowel disease or allergies, emphasizing how gut health can affect systemic immunity.

Related terms

Antigen Presentation: The process by which dendritic cells and other antigen-presenting cells display foreign antigens on their surface to T cells, enabling the activation of adaptive immunity.

T cells:

A type of white blood cell that plays a central role in cell-mediated immunity; T cells are activated by dendritic cells and can directly kill infected host cells or help orchestrate the immune response.

Innate Immunity: The body's first line of defense against pathogens, involving nonspecific mechanisms like physical barriers, phagocytic cells, and the inflammatory response, where dendritic cells play an important role in sensing threats.