C1 esterase inhibitor is a single chain glycoprotein which inhibits C1, C1r, C1s, plasma kallikrein, factors XIa, XIIa and plasmin of the blood clotting system. It is present in the plasma at 16-33 mg/100mL. It is part of the serpin family.
Esterase inhibitor C1 is a multifunctional regulator of all major kinin-generating protein cascade systems. It has been a therapeutic tool in the treatment of hereditary angioedema and complement-mediated inflammatory tissue damage such as capillary leak syndrome, septic shock, multiple organ failure, and hyperacute graft rejection.
