Mouse α₁-protease inhibitor is not an acute phase reactant

Mouse plasma contains two major protease inhibitors, α1-protease inhibitor (α1-PI) and contrapsin, which have high affinity for bovine trypsin. Systemic injury, such as turpentine-induced inflammation, did not change the plasma concentration of α1-PI, but increased that of contrapsin by 50%. The concentration of hepatic α1-PI mRNA was determined by Northern blot hybridization and was not significantly affected by the acute phase reaction. J. M. Frazer, S. A. Nathoo, J. Katz, T. L. Genetta, and T. H. Finley ((1985) Arch. Biochem. Biophys. 239, 112-119) have reported a threefold increase of mRNA for the elastase specific α1-PI but this increase was not demonstrated by the present study. The mRNAs for known mouse acute phase plasma proteins were, however, stimulated severalfold by the same treatment. These results indicate that in the mouse, as opposed to human, α1-PI is not an acute phase reactant.