δ chain

Definition

The δ chain is a type of heavy chain found in a subset of T cell receptors (TCRs) that are expressed on a specialized population of T cells known as γδ T cells. The δ chain, along with the γ chain, forms the TCR complex that allows γδ T cells to recognize and respond to a variety of antigens.

5 Must Know Facts For Your Next Test

1. The δ chain is one of the two types of heavy chains that can be found in the T cell receptor (TCR) complex, the other being the α chain.
2. γδ T cells, which express the δ chain in their TCR, play a role in both the innate and adaptive immune responses, recognizing a diverse array of antigens.
3. Unlike conventional αβ T cells, γδ T cells do not require antigen presentation by major histocompatibility complex (MHC) molecules to be activated.
4. The δ chain, along with the γ chain, forms a TCR that can recognize and respond to a variety of stress-induced, microbial, and tumor-associated antigens.
5. γδ T cells expressing the δ chain are found in various tissues, including the skin, intestines, and reproductive organs, where they help maintain epithelial integrity and provide immediate immune responses.

Review Questions

• Explain the role of the δ chain in the T cell receptor (TCR) complex and its significance in the function of γδ T cells.
  • The δ chain is one of the two heavy chains that can be found in the T cell receptor (TCR) complex, the other being the α chain. The δ chain, along with the γ chain, forms the TCR expressed on a specialized subset of T cells known as γδ T cells. Unlike conventional αβ T cells, γδ T cells do not require antigen presentation by major histocompatibility complex (MHC) molecules to be activated. The δ chain-containing TCR allows γδ T cells to recognize and respond to a diverse array of antigens, including stress-induced, microbial, and tumor-associated molecules. This unique TCR composition and antigen recognition capability enables γδ T cells to play a crucial role in both the innate and adaptive immune responses, helping to maintain epithelial integrity and providing immediate immune responses in various tissues.
• Describe the differences between γδ T cells and conventional αβ T cells in terms of their T cell receptor (TCR) composition and antigen recognition.
  • The key difference between γδ T cells and conventional αβ T cells lies in the composition of their T cell receptor (TCR) complex. While αβ T cells express a TCR composed of α and β chains, γδ T cells express a TCR made up of γ and δ chains. This distinct TCR composition allows γδ T cells to recognize and respond to a wider range of antigens, including stress-induced, microbial, and tumor-associated molecules, without the requirement for antigen presentation by major histocompatibility complex (MHC) molecules. In contrast, conventional αβ T cells rely on MHC-presented antigens to become activated. The unique antigen recognition capabilities of γδ T cells, facilitated by the δ chain in their TCR, enable them to play a crucial role in both the innate and adaptive immune responses, providing immediate protection and maintaining epithelial integrity in various tissues.
• Analyze the significance of the δ chain in the context of B lymphocytes and humoral immunity, and explain how this relates to the overall immune response.
  • While the δ chain is primarily associated with T cell receptor (TCR) composition and the function of γδ T cells, it does not have a direct role in B lymphocytes or humoral immunity. The δ chain is specific to the TCR complex and is not found in the B cell receptor (BCR) expressed on the surface of B cells. However, the δ chain-containing TCR of γδ T cells does contribute to the overall immune response, including the humoral immune response mediated by B cells. γδ T cells can interact with and support the activation and differentiation of B cells, leading to the production of antibodies. Additionally, the antigens recognized by γδ T cells, facilitated by the δ chain in their TCR, can provide important signals and stimuli that help shape the humoral immune response against various pathogens and disease states. Therefore, while the δ chain is not directly involved in B cell function, it plays an indirect role in modulating the humoral immune response through the unique antigen recognition capabilities of γδ T cells.

Related terms

T cell receptor (TCR): The TCR is a protein complex found on the surface of T cells that is responsible for recognizing and binding to specific antigens presented by major histocompatibility complex (MHC) molecules.

γδ T cells: γδ T cells are a unique subset of T cells that express a TCR composed of γ and δ chains, rather than the more common α and β chains found in conventional T cells.

Antigen: An antigen is a molecule or substance that can be recognized by the immune system, triggering an immune response.