Cell-mediated immunity

Definition

Cell-mediated immunity is an immune response that does not involve antibodies but instead relies on the activation of T-cells to fight pathogens. It plays a crucial role in defending against intracellular pathogens and cancer cells.

5 Must Know Facts For Your Next Test

1. Cell-mediated immunity primarily involves T-lymphocytes, including helper T-cells and cytotoxic T-cells.
2. Helper T-cells (CD4+) assist other immune cells by releasing cytokines, while cytotoxic T-cells (CD8+) directly kill infected or cancerous cells.
3. This type of immunity is crucial for controlling infections caused by viruses, some bacteria, and fungi that reside inside host cells.
4. Immunosuppressive drugs can inhibit cell-mediated immunity, which can be beneficial in preventing organ transplant rejection but may increase the risk of infections.
5. Cell-mediated immunity is often measured through tests like the Tuberculin Skin Test (TST) or Interferon-Gamma Release Assays (IGRAs) to detect latent tuberculosis.

Review Questions

• What are the primary cells involved in cell-mediated immunity?
• How do cytotoxic T-cells contribute to cell-mediated immunity?
• Why is cell-mediated immunity important in fighting intracellular pathogens?

Related terms

Humoral Immunity:

An immune response involving antibodies produced by B-cells to neutralize pathogens.

Cytokines:

Small proteins released by cells that have a specific effect on interactions and communications between cells.

Antigen-Presenting Cells (APCs):

Cells such as dendritic cells, macrophages, and B-cells that process antigens and present them to T-cells to initiate an immune response.