α1 Antichymotrypsin
α1 Antichymotrypsin (ACT) belongs to the α1-globulin family of human plasma proteins. It functions as a specific inhibitor of chymotrypsin and other serine proteases. Normal levels in human serum are 25-40mg/dL. ACT is an acute phase protein found in hepatocytes, macrophages, and epithelial, endothelial, and mast cells.
ACT is a major component of the amyloid deposits associated with Alzheimer’s disease. In addition, elevated levels are found in various inflammatory conditions including Crohn’s disease, ulcerative colitis and burn injuries. The association of ACT and PSA is being investigated in the diagnosis of prostate cancer. ACT naturally complexes with PSA in human serum.