Alpha 1-antitrypsin is a glycoprotein primarily produced by hepatocytes, and to a lesser extent, immune system cells. The product is produced from yeast, which unlike commercially available forms of plasma-derived AAT, eliminates the risk associated with blood-borne infectious agents and allows for a increased manufacturing. rAAT belongs to a family of structurally-related proteins classified as serine protease inhibitors or SERPINS, which are known to inhibit several proteases including trypsin, cathepsin G, thrombin, tissue kallikrein, as well as neutrophil elastase.