{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Perforin is a cytolytic glycoprotein found in the granules of cytotoxic T cells and natural killer cells. Upon degranulation, perforins undergo polymerization, insert themselves into the target cell’s plasma membrane, and form pores in a series of processes mediated by Ca2+. The free influx and efflux of ions and polypeptides disturbs homeostasis and results in tonic shock. Granzyme can also enter the target cells and activate apoptosis and DNA degradation, leading to cell death. The role of perforin-mediated cytotoxicity has been demonstrated in various autoimmune diseases and allogeneic transplant rejection. Perforin mutation can cause familial hemophagocytic lymphohistiocytosis (HLH) while a partial deficiency in perforin synthesis might be the cause of increased susceptibility to leukemias and lymphomas."}]}]}