A cytotoxic T cell (also known as TC, Cytotoxic T Lymphocyte, CTL, T-Killer cell, cytolytic T cell, CD8+ T-cells or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways.
Most cytotoxic T cells express T-cell receptors (TCRs) that can recognize a specific antigen. An antigen is a molecule capable of stimulating an immune response, and is often produced by cancer cells or viruses. Antigens inside a cell are bound to Class I MHC molecules, and brought to the surface of the cell by the Class I MHC molecule, where they can be recognized by the T cell. If the TCR is specific for that antigen, it binds to the complex of the Class I MHC molecule and the antigen and the T cell destroys the cell.
In order for the TCR to bind to the Class I MHC molecule, it must be accompanied by a glycoprotein called CD8, which binds to the constant portion of the Class I MHC molecule. Therefore, these T cells are called CD8+ T cells.
The affinity between CD8 and the MHC molecule keeps the TC cell and the target cell bound closely together during antigen-specific activation. CD8+ T cells are recognized as TC cells once they become activated and are generally classified as having a pre-defined cytotoxic role within the immune system. However, CD8+ T cells also have the ability to make some cytokines.
Read more about Cytotoxic T Cell: Development, Activation, Effector Functions, Role in Disease Pathogenesis
Famous quotes containing the word cell:
“It is plain that there is no separate essence called courage, no cup or cell in the brain, no vessel in the heart containing drops or atoms that make or give this virtue; but it is the right or healthy state of every man, when he is free to do that which is constitutional to him to do.”
—Ralph Waldo Emerson (1803–1882)