Dendritic Cells

Definition

Dendritic cells are a type of antigen-presenting cell that play a crucial role in the initiation and regulation of the immune response. They are found in tissues that are in contact with the external environment, such as the skin, and act as sentinels, constantly sampling their surroundings for potential threats.

5 Must Know Facts For Your Next Test

1. Dendritic cells are found in most tissues, with high concentrations in the skin, lungs, and gastrointestinal tract, where they can encounter and process foreign antigens.
2. They are derived from bone marrow precursor cells and can differentiate into various subtypes, such as myeloid dendritic cells and plasmacytoid dendritic cells.
3. Dendritic cells are highly efficient at capturing, processing, and presenting antigens to T cells, which is a crucial step in activating the adaptive immune response.
4. Upon encountering a pathogen, dendritic cells undergo maturation, upregulating co-stimulatory molecules and secreting cytokines that promote the activation and differentiation of T cells.
5. Dendritic cells play a key role in maintaining immune tolerance by presenting self-antigens to T cells, which can lead to the deletion or inactivation of self-reactive T cells.

Review Questions

• Describe the role of dendritic cells in the initiation of the immune response.
  • Dendritic cells are the primary antigen-presenting cells responsible for initiating the immune response. They patrol the body, constantly sampling their environment for foreign antigens. Upon encountering a pathogen, dendritic cells undergo maturation, upregulating co-stimulatory molecules and secreting cytokines that activate and direct the differentiation of naive T cells. This allows dendritic cells to bridge the gap between the innate and adaptive immune systems, triggering a targeted response against the identified threat.
• Explain the importance of dendritic cell subtypes and their specialized functions.
  • Dendritic cells can differentiate into various subtypes, each with distinct functions and roles in the immune response. Myeloid dendritic cells are efficient at presenting antigens and activating T cells, while plasmacytoid dendritic cells are specialized in producing large amounts of type I interferons, which play a crucial role in antiviral immunity. The diversity of dendritic cell subtypes allows for a more nuanced and specialized immune response, tailored to the specific threat encountered. This specialization is essential for maintaining immune homeostasis and preventing autoimmune diseases.
• Discuss the role of dendritic cells in maintaining immune tolerance and preventing autoimmunity.
  • In addition to their role in initiating immune responses, dendritic cells also play a critical part in maintaining immune tolerance. By presenting self-antigens to T cells, dendritic cells can lead to the deletion or inactivation of self-reactive T cells, preventing them from attacking the body's own tissues. This process of central tolerance is essential for avoiding autoimmune diseases. Dendritic cells also induce the differentiation of regulatory T cells, which further suppress the activation of self-reactive T cells in the periphery. The delicate balance between dendritic cell-mediated activation of the immune system and induction of tolerance is crucial for maintaining homeostasis and preventing autoimmunity.

Related terms

Antigen-Presenting Cells: Cells that display foreign antigens on their surface, allowing them to be recognized by T cells and initiate an immune response.

Innate Immunity: The body's first line of defense against pathogens, which includes physical barriers, chemical defenses, and immune cells like dendritic cells.

Adaptive Immunity: The body's second line of defense, which involves the activation of specialized lymphocytes (T and B cells) to mount a targeted response against specific pathogens.