Cytotoxic T Cells: The Killing Blow

This is a fourth image in Audra Geras’ immunology series exploring the amazing human immune system

The art features the precise mechanisms by which cytotoxic T cells are able to kill transformed (cancerous) cells, virus-infected cells, as well as some cells with other pathologies.

Perforin molecules being released from a cytotoxic T cell vesicle.

Perforin molecules forming a pore in the cell membrane of a target cell.

Cytotoxic T cells (green) store perforin (peach) and granzyme (orange) molecules within lysosome vesicles. In response to recognition of a specific antigen presented by MHC molecules on the surface of a target cell, cytotoxic T cells secrete these molecules into the extracellular space by a target cell.

Perforin molecules insert themselves into the target cell membrane and assemble into membrane pores via polymerization. This creation of pores into the target cell allows for several lethal effects. Death of a target cell happens either because of an uncontrolled influx of calcium ions (blue), increasing osmotic stress, or by the influx of cytotoxic granzymes. Perforin and granzymes work cooperatively to cause the death of target cells. Cell death may occur via necrosis, lysis or apoptosis depending on the specific trigger.

In the bottom right corner, a target cell is seen undergoing lysis caused by its interaction with a highly specific cytotoxic T cell.