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CD8 T cell
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The CD8 T cell is the white blood cell that kills. It is also called cytotoxic, which means toxic to cells, or simply the killer cell. While its sibling the CD4 cell organizes everyone else, this one does the killing.
To know whom to kill it has an elegant trick. Almost every cell in the body, if it has a nucleus, goes around showing on its surface samples of what it makes inside, mounted on platforms called MHC class 1. It is as if every cell wore a badge with its contents written on it. The CD8 cell goes around checking: it is an inspector who asks for ID at every door and acts only if the badge is fake. If what it sees is a piece of a virus, it knows that cell is infected.
Then it kills it, and it does so by two routes. In one it displays a piece called FasL that fits into a receptor called Fas on the diseased cell, and with that it triggers the cell's self-destruction. In the other it releases granzymes and perforin onto the cell, and that pair of molecules is what finishes it off.
In brief
The CD8 T cell, also called the cytotoxic or killer cell, is an effector cell of cell-mediated immunity: it kills the diseased cell.
It reads the peptides that every nucleated cell displays on its MHC class 1 molecules, the route by which the immune system detects an infected cell.
An inspector who asks for ID at every door and acts only if the badge is fake.
It kills by two routes: FasL on the Fas receptor, or a release of granzymes and perforin.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingHistology, T-Cell Lymphocyte, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, MHC Class I, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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