Cytotoxic T cell

A cytotoxic (or T_C) T cell is a T cell (a type of white blood cell) which has on its surface antigen receptors that can bind to fragments of antigens displayed by the Class I MHC molecules of infected somatic cells.

Once bound to an antigen, T_C cells release the protein perforin, which forms pores in the target cell's plasma membrane; this causes ions and water to flow into the target cell, making it expand and eventually lyse.

Most T_C cells have present on the cell surface the protein CD8, which is attracted to portions of the Class I MHC molecule. This affinity keeps the T_C cell and the target cell bound closely together during antigen-specific activation. T_C cells with CD8 surface protein are called CD8+ T cells.

See also:

• T cell
• White blood cell