Ontogeny and tissue distribution of alpha-1-antitrypsin of the mouse

alpha 1-Antitrypsin is the second most abundant proteinase inhibitor in plasma. The fact that it is a globular glycoprotein of relatively small size (Mr 53 500) allows it access to a wide variety of fluids and tissue sites. alpha 1-Antitrypsin has been purified from mouse plasma by affinity chromatography and ion exchange. The purified protein exhibits homogeneity on polyacrylamide electrophoresis, but electrophoretic heterogeneity on crossed immunoelectrophoresis. Mouse and rat alpha 1-antitrypsin show strong crossreactivity and the half-life for mouse alpha 1-antitrypsin is 15.5 h. Fetal levels are 15% of adult and it requires 25--30 days before adult levels are reached in the neonate. Maternal levels remain unchanged throughout pregnancy and at parturition. The inhibitory is presented in a number of body fluids including serum, breast milk, gastrointestinal washing, lung washings and bile. The source of alpha 1-antitrypsin for all of these fluids appears to be the liver.