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

Abstract

$\text{α}{}_1\text{-}\text{Antitrypsin}$ is the second most abundant proteinase inhibitor in plasma. The fact that it is a globular glycoprotein of relatively small size ($\text{M}{}_{\mathrm{<mtext>r</mtext>}}$ 53 500) allows it access to a wide variety of fluids and tissue sites. $\text{α}{}_1\text{-}\text{Antitrypsin}$ 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 immuno-electrophoresis. Mouse and rat $\text{α}{}_1\text{-}\text{antitrypsin}$ show strong crossreactivity and the half-life for mouse $\text{α}{}_1\text{-}\text{antitrypsin}$ 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 inhibitor is present in a number of body fluids including serum, breast milk, gastrointestinal washings, lung washings and bile. The source of $\text{α}{}_1\text{-}\text{antitrypsin}$ for all of these fluids appears to be the liver.