Helper T cells

Definition

Helper T cells are a type of T lymphocyte that play a central role in the adaptive immune response by activating other immune cells. They are essential for initiating and regulating both cellular and humoral immunity.

5 Must Know Facts For Your Next Test

1. Helper T cells express the CD4 molecule on their surface, distinguishing them from other T cells.
2. They recognize antigens presented by MHC class II molecules on antigen-presenting cells (APCs).
3. Activated helper T cells secrete cytokines that influence the activity of other immune cells such as cytotoxic T cells, B cells, and macrophages.
4. Th1 and Th2 are two major subsets of helper T cells, each producing different sets of cytokines to direct specific immune responses.
5. HIV targets CD4+ helper T cells, leading to a weakened immune system in infected individuals.

Review Questions

• What molecule do helper T cells express on their surface?
• Which type of MHC molecule presents antigens to helper T cells?
• How do activated helper T cells assist in the immune response?

Related terms

Cytotoxic T Cells: A type of T cell that kills infected or cancerous cells by inducing apoptosis.

B Lymphocytes: White blood cells responsible for producing antibodies as part of the humoral immune response.

Cytokines: Signaling proteins released by cells to communicate and coordinate an immune response.