Glycoprotein found in alpha(1)-globulin region in human serum. It inhibits chymotrypsin-like proteinases in vivo and has cytotoxic killer-cell activity in vitro. The protein also has a role as an acute-phase protein and is active in the control of immunologic and inflammatory processes, and as a tumor marker. It is a member of the serpin superfamily.

Synonyms: 0, alpha 1-Antichymotrypsin, alpha(1)-Antichymotrypsin, Serpin A3, alpha 1 Antichymotrypsin