Alpha 1 Antichymotrypsin, Human Plasma

Alpha 1 antichymotrypsin is an acute-phase plasma protein found at 45 mg per 100 ml. ACT functions as a specific inhibitor of chymotrypsin-like serine proteases. Although its physiological function is unclear, it can inhibit neutrophil cathepsin G and mast cell chymase, both of which can convert angiotensin-1 to the active angiotensin-2. Clinically, it is elevated in inflammatory conditions, some malignancies, Crohn's disease, ulcerative colitis, and burn injuries. The PSA-ACT complex level is considered a biomarker for prostate cancer. Defects in this gene may be a cause of chronic obstructive pulmonary disease.