α1-antitrypsin, also called “α1-protease inhibitor”, is a protein of the serpin family, which is synthesised predominantly in the liver by hepatocytes. Its main role is to inhibit neutrophil elastase and thereby prevent enzyme degradation of the lung alveolar structures. It also enables the inhibition of other proteolytic enzymes such as trypsin, chymotrypsin, and thrombin.
α1-antitrypsin is an early inflammatory phase protein; therefore its concentration increases drastically in case of inflammation.
α1-antitrypsin deficiency, which may be the result of a genetic variation, reduces proteolytic enzyme inhibition, and can lead to pulmonary emphysema or liver disease. Low levels of α1-antitrypsin may also be associated with cirrhosis, cancers of the liver, or juvenile hepatitis.