CD8+ T-Lymphocytes

Obi Wan Kenobi representing a memory CD8+ T-lymphocyte Obi Wan has previously fought and killed the imperial troops remembering their weaknesses. He leads the battle to destroy the threat.

CD8+ T-lymphocytes, also known as cytotoxic or killer T-lymphocytes are one of two main types of T-lymphocytes in the body, the other being CD4+ T-lymphocytes. CD8+ T-lymphocytes, as their name suggests, kill other cells in the body that have become infected, damaged or diseased.

To identify body cells that need to be destroyed, CD8+ T-lymphocytes recognise a small fragment of the target cell presented to them by a surface molecule called Major Histocompatibility Complex (MHC) Class I. The fragment that is presented is specific to a pathogen or to a type of damaged or diseased cell, allowing for a highly targeted immune response. All nucleated cells in the body express this molecule and binding of the MHC Class 1 molecule expressing the correct fragment with a complimentary T-Cell Receptor (TCR) expressed on the CD8+ T-lymphocyte results in clonal expansion followed by the release of chemicals or activation of signalling pathways that result in the death of the target cell through a process known as apoptosis, or programmed cell death.

Clonal expansion also results in the formation of memory cells that are longer-lived and allow for a more targeted immune response if the same threat is encountered again.

CD8+ T-lymphocytes are very important in the defence against intracellular pathogens, such as bacteria or viruses, where proteins from the invading organism are expressed in the host MHC Class I molecules. CD8+ T0-lymphocytes are also involved in the removal of cancerous cells, which express abnormal protein fragments in the MHC complex, which are not displayed by healthy cells.

Cells

Tissues

Soluble Mediators

Pathogens

Vaccination