ABSTRACT
Alpha 1-antitrypsin (alAT) is the major physiological inhibitor of neutrophil elastase, an enzyme capable of degrading many constituents of the extracellular matrix. The net concentration of a 1 AT in plasma and tissues is, therefore, thought to be an important determinant of tissue remodeling during homeostasis, tissue injury, and inflammation. Although plasma a l AT is derived predominantly from the liver, as shown by changes in allotype after orthotopic liver transplantation, there are also extrahepatic sites of its synthesis (1,2). We have demonstrated expression of the alAT gene in human monocytes, bronchoalveolar and breastmilk macrophages, and enterocytes (3-5). Because monocytes can be relatively easily obtained from human donors, the study of alA T synthesis in these cells has provided further understanding of several aspects of the biology and pathobiology of this protein.
