Perforin is a pore-forming glycoprotein that helps Killer T cells and NK cells kill infected or abnormal target cells by forming pores in their membranes.
This allows granzymes to enter target cells and induce apoptosis (programmed cell death).
While primarily secreted by CD8+ cytotoxic T cells and NK cells, CD4+ T cells can also produce perforin but in smaller amounts under specific conditions.
