Perforin is a pore-forming protein, and its transmembrane channel formation mechanism is similar to that of C9. It has been proven that perforin is homologous to C9. Studies have shown that perforin is expressed only in cytotoxic cell lines and not in helper T lymphocytes or other tested tumor cells. It is well known that perforin is a key effector molecule in T cell and natural killer cell-mediated cytotoxicity. Defects in the perforin gene lead to familial hemophagocytic lymphohistiocytosis type 2 (HPLH2), a rare and fatal autosomal recessive genetic disease in early childhood. Alternative splicing leads to multiple transcriptional variants of perforin.
