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.



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