How do CD8 cells execute their cytotoxic function?

CD8 T cells, also known as cytotoxic T lymphocytes, are specifically designed to eliminate infected or cancerous cells. Their cytotoxic function is primarily executed through several key effector molecules, including perforin, granzyme, granulysin, and Fas ligand.

When CD8 T cells recognize a target cell that presents the appropriate antigen via MHC class I molecules, they engage in direct cytotoxicity. Perforin is released by the CD8 T cells and forms pores in the target cell membrane. This pore formation allows granzyme, a serine protease, to enter the target cell, where it initiates apoptosis (programmed cell death) by activating intracellular apoptotic pathways.

Granulysin also has cytotoxic properties; it can enter the target cell and induce apoptosis as well, while also having antimicrobial effects against some pathogens. The Fas ligand interaction with the Fas receptor on the target cell is another crucial pathway that signals apoptosis, allowing for targeted destruction of cells that are infected or dysfunctional.

In summary, the cytotoxic activity of CD8 T cells is a sophisticated and coordinated mechanism involving the release of specific cytolytic proteins and factors that induce cell death, ensuring the removal of harmful cells from the organism.