How do cytotoxic lymphocytes kill their targets?

CD8⁺ cytotoxic lymphocytes, natural killer cells and lymphokine-activated killer cells depend primarily on the perforin/granzyme system to kill their targets, while CD4⁺ T cells utilize Fas and other mechanisms to induce cell death. The molecular mechanisms used by these pathways to induce target cell apoptosis may converge on common death substrates.