Cytotoxic T-cells
Cytotoxic T cells are able to search the intracellular compartments to remove or destroy any foreign objects such as bacteria and pathogens which have the potential to cause harm. Also known as a killer T-cell. These cells kill host cells that have become infected by some sort of intracellular pathogen[1].
The cytotoxic T-cells can trigger an endogenous pathway within the target cell leading to apoptosis. This is due to the cytotoxic T-cells releasing "preformed effector molecules"[2][3].