CD4+ T cells

Definition

CD4+ T cells are a type of immune cell that play a critical role in the adaptive immune response by helping other cells in the immune system respond to infections. These cells are characterized by the presence of the CD4 glycoprotein on their surface, which acts as a co-receptor for the T cell receptor (TCR). They are essential for orchestrating the immune response, including activating B cells to produce antibodies and stimulating CD8+ T cells to kill infected cells.

5 Must Know Facts For Your Next Test

1. CD4+ T cells are crucial for both cellular and humoral immunity, aiding in both direct cell-mediated responses and antibody production.
2. They recognize antigens presented by MHC class II molecules on APCs, which is essential for their activation.
3. The activation of CD4+ T cells leads to their proliferation and differentiation into various subsets, such as Th1, Th2, and Th17, each with distinct functions.
4. HIV specifically targets CD4+ T cells, leading to immunodeficiency and making individuals susceptible to opportunistic infections.
5. Therapies that involve CD4+ T cells are being developed for treatments like cancer immunotherapy, where they can help enhance the body’s ability to fight tumors.

Review Questions

• How do CD4+ T cells assist in the immune response?
  • CD4+ T cells assist in the immune response by recognizing antigens presented by MHC class II molecules on antigen presenting cells (APCs). Once activated, they proliferate and differentiate into various subtypes that help activate B cells to produce antibodies and stimulate cytotoxic CD8+ T cells to eliminate infected or cancerous cells. Their role is vital in coordinating an effective adaptive immune response.
• Discuss the impact of HIV infection on CD4+ T cell populations and overall immunity.
  • HIV infection leads to a significant decrease in CD4+ T cell populations as the virus specifically targets these cells for destruction. This depletion compromises the immune system's ability to respond effectively to infections, making individuals more vulnerable to opportunistic pathogens. The decline of CD4+ T cells is a hallmark of AIDS, highlighting their crucial role in maintaining immune function.
• Evaluate the potential of utilizing CD4+ T cells in cancer immunotherapy strategies.
  • Utilizing CD4+ T cells in cancer immunotherapy presents promising potential due to their ability to coordinate the immune response against tumors. By enhancing the activation and proliferation of these helper T cells, therapies can improve the overall effectiveness of the immune system in recognizing and attacking cancerous cells. This approach not only aims to boost direct cytotoxic responses from other immune cells but also supports antibody production through activated B cells, offering a multi-faceted attack on tumors.

Related terms

Helper T cells: A subset of CD4+ T cells that assist in activating and regulating other immune cells, playing a key role in coordinating the adaptive immune response.

Cytotoxic T cells: Also known as CD8+ T cells, these are another type of T cell that directly kill infected or cancerous cells.

Antigen presenting cells (APCs): Cells that display antigens to CD4+ T cells, which is crucial for their activation. Examples include dendritic cells, macrophages, and B cells.