Helper T cells

Definition

Helper T cells are a type of white blood cell that play a crucial role in the immune response by assisting other immune cells in recognizing and responding to pathogens. They are primarily responsible for activating B cells to produce antibodies and stimulating cytotoxic T cells to kill infected cells. These cells are essential for orchestrating the adaptive immune response, ensuring that the body can effectively combat infections and maintain immunological memory.

5 Must Know Facts For Your Next Test

1. Helper T cells express the CD4 glycoprotein on their surface, which distinguishes them from other T cell types and helps them interact with antigen presenting cells.
2. They secrete signaling molecules called cytokines that enhance the immune response by promoting the activation and differentiation of other immune cells.
3. Helper T cells are essential for establishing immunological memory, allowing the immune system to respond more effectively to previously encountered pathogens.
4. There are different subsets of helper T cells, such as Th1, Th2, Th17, each with specialized functions in directing the immune response.
5. HIV specifically targets helper T cells, leading to their depletion and resulting in a weakened immune system, which is characteristic of AIDS.

Review Questions

• How do helper T cells facilitate the immune response and what roles do they play in activating other immune cells?
  • Helper T cells facilitate the immune response by recognizing specific antigens presented by antigen presenting cells through their CD4 receptors. Once activated, they release cytokines that stimulate B cells to produce antibodies and activate cytotoxic T cells to destroy infected or cancerous cells. This coordination is vital for mounting an effective adaptive immune response against pathogens.
• Compare the roles of helper T cells and cytotoxic T cells in the adaptive immune response.
  • Helper T cells primarily serve as coordinators of the immune response by activating and directing other immune cells through cytokine signaling. In contrast, cytotoxic T cells directly target and kill infected or cancerous cells. While helper T cells ensure that B cells produce antibodies and enhance the activity of cytotoxic T cells, cytotoxic T cells execute the killing of infected host cells, demonstrating a clear division of labor within the adaptive immune system.
• Evaluate the impact of helper T cell depletion in diseases like HIV/AIDS on overall immune function.
  • The depletion of helper T cells in diseases like HIV/AIDS has a profound impact on overall immune function. Since these cells are critical for activating B cells and cytotoxic T cells, their loss results in a severely compromised adaptive immune response. Patients with low helper T cell counts struggle to mount effective responses to infections and cannot develop immunological memory, making them highly susceptible to opportunistic infections and certain cancers, leading to significantly increased morbidity and mortality rates.

Related terms

Cytotoxic T cells: A subtype of T lymphocytes that directly kill infected or cancerous cells by recognizing specific antigens presented on their surfaces.

B cells:

A type of white blood cell that produces antibodies in response to antigens, playing a vital role in the humoral immune response.

Antigen presenting cells (APCs): Cells that display antigens on their surfaces to activate T cells, including dendritic cells, macrophages, and B cells.