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Biochemistry

The inhibitor is mainly responsible for the inhibition of the activity of PMN-elastase in plasma. About 90% of the elastase in plasma is inhibited by α₁-antitrypsin. Although it also inhibits various other serine proteases, as e.g. thrombin, factor XIa, trypsin and activated protein C (APC), α₁-antitrypsin is of no significance in the coagulation system.

Clinical significance

Reduced concentrations are observed in patients with sepsis or multi-organ failure as well as in some genetic lung and liver diseases. As an acute phase protein, increased concentrations of α₁-antitrypsin can be determined is some situations. Inherited deficiency may cause liver disease and lung emphysema at an early age.

Indication

• Control of sepsis and multi-organ failure
• Monitoring of the elastase-inhibiting potential
• Screening of newborns for α₁-antitrypsin deficiency

Literature

1. Friberger P. Chromogenic peptide substrates. Their use for the assay of factors in the fibrinolytic and plasma kallikrein-kinin systems. Scand J Clin Lab Invest 42, Suppl 162, 84-85, 1982.
2. Gallimore MJ, Aurell L, Friberger P, Gustavsson S. Chromogenic peptide substrate sassys for determining functional activities of ?2-macroglobulin and α₁-antitrypsin using a new trypsin substrate. Thromb Haemost 50, 230, 1983.
3. Ohlsson K, Olsson A-S. Immunoreactive granulocyte in human serum. Hoppe-Seyler's Z Physiol Chem 359, 1531, 1978.
4. Heck LW, Kaplan AP. Substrates of Hageman factor: I. Isolation and characterization of human factor XI (PTA) and inhibition of the activated enzyme by alpha-1-antitrypsin. J Exp Med 140, 1615, 1974.
5. Heeb MJ, Griffin JH. Physiologic inhibition of human activated protein C by alpha-1-antitrypsin. J Biol Chem 263, 11613-11616, 1988.
6. Sveger T, Thelin T. A future for neonatal alpha 1-antitrypsin screening? Acta Pediatr 89 (3), 259-261, 2000.