Langerhans cells

Definition

Langerhans cells are specialized dendritic cells found primarily in the skin that play a crucial role in the immune system by capturing and presenting antigens to T cells. These cells are essential components of skin-associated lymphoid tissue (SALT), acting as sentinels that help initiate immune responses against pathogens while maintaining tolerance to harmless substances.

5 Must Know Facts For Your Next Test

1. Langerhans cells originate from the bone marrow and migrate to the skin, where they reside in the epidermis.
2. These cells have a unique morphology characterized by long, dendritic projections that facilitate their interaction with T cells.
3. Upon encountering pathogens, Langerhans cells can internalize antigens and migrate to nearby lymph nodes to activate T cell responses.
4. Langerhans cells also help maintain peripheral tolerance by preventing overactive immune responses against non-harmful antigens like food proteins or skin microbiota.
5. They express various surface markers, including CD1a and Langerin, which help distinguish them from other dendritic cells.

Review Questions

• How do Langerhans cells contribute to both immune defense and tolerance in the skin?
  • Langerhans cells play a dual role in skin immunity. They act as first responders that capture and present antigens from pathogens to T cells, initiating an adaptive immune response. At the same time, they maintain peripheral tolerance by recognizing non-harmful antigens and preventing unnecessary immune activation. This balance is crucial for protecting the body while avoiding excessive inflammation or allergic reactions.
• Discuss the migration process of Langerhans cells after antigen capture and its significance in immune activation.
  • After Langerhans cells capture antigens in the skin, they undergo maturation and migrate to regional lymph nodes. During this migration, they change their surface markers and upregulate molecules necessary for effective T cell activation. This process is significant because it ensures that T cells can recognize and respond to specific pathogens while also allowing Langerhans cells to communicate critical information about the nature of the threat to other immune cells.
• Evaluate the implications of dysfunctional Langerhans cell activity in skin-related diseases.
  • Dysfunction in Langerhans cell activity can lead to various skin-related diseases, including allergies, autoimmune conditions, and infections. For example, inadequate antigen presentation may result in an insufficient immune response against pathogens, allowing infections to flourish. Conversely, overactive Langerhans cell function can contribute to autoimmune responses where the body mistakenly attacks its own tissues. Understanding these implications helps guide therapeutic strategies for managing skin disorders.

Related terms

Dendritic Cells:

A type of antigen-presenting cell that processes and presents antigens to T cells, playing a vital role in the initiation of adaptive immune responses.

Antigen Presentation:

The process by which dendritic cells, including Langerhans cells, capture antigens and present them on major histocompatibility complex (MHC) molecules to T cells.

Skin-associated lymphoid tissue (SALT): A network of immune cells located in the skin that participates in the immune response, including Langerhans cells and other types of immune cells.