T lymphocytes

Definition

T lymphocytes, or T cells, are a type of white blood cell essential for the adaptive immune response. They originate in the bone marrow and mature in the thymus.

5 Must Know Facts For Your Next Test

1. T cells are divided into two main types: helper T cells (CD4+) and cytotoxic T cells (CD8+).
2. Helper T cells assist other immune cells by releasing cytokines, which enhance the immune response.
3. Cytotoxic T cells directly kill infected or cancerous cells by inducing apoptosis.
4. T cell receptors (TCRs) on the surface of T lymphocytes recognize specific antigens presented by major histocompatibility complex (MHC) molecules.
5. Regulatory T cells (Tregs) help maintain immune tolerance and prevent autoimmune diseases.

Review Questions

• What are the two main types of T lymphocytes and their primary functions?
• How do cytotoxic T cells eliminate infected cells?
• What role do regulatory T cells play in the immune system?

Related terms

B lymphocytes:

White blood cells that produce antibodies as part of the humoral immune response.

Antigen-presenting cells (APCs): Cells such as macrophages and dendritic cells that process and present antigens to T lymphocytes.

Major Histocompatibility Complex (MHC):

Proteins on cell surfaces that present antigen fragments to T cell receptors.