Hepatic α1‐antitrypsin mRNA content in cirrhosis with normal and abnormal protease inhibitor phenotypes

We quantitated α 1 ‐antitrypsin mRNA in normal, α 1 ‐antitrypsin‐deficient cirrhotic and biliary cirrhotic livers using two‐dimensional electrophoretograms of [ 35 S ] methionine‐labeled translational products of total hepatic RNA and RNA/DNA hybridization. α 1 ‐antitrypsin precursor product was identified by immunoprecipitation. The relative abundance of α 1 ‐antitrypsin product from normal (0.989 ± 0.197), cirrhotic (0.956 ± 0.062) and α 1 ‐antitrypsin deficient (0.818 ± 0.12) livers was not significantly different. Although (RNA/DNA) was decreased in the PiZZ cirrhotic livers compared to normal (0.56 ± 0.045 vs. 0.95 ± 0.225), it equaled that found in the PiM cirrhotic livers (0.56 ± 0.055). The concentration of α 1 ‐antitrypsin mRNA [relative abundance × (RNA/DNA)], while decreased in PiZZ compared to normal liver, is thus no different in PiZZ cirrhotics than in PiM cirrhotics. We confirmed this observation by quantitation of the α 1 ‐antitrypsin mRNA using an α 1 ‐antitrypsin genomic probe. By RNA/DNA hybridization, α 1 ‐antitrypsin mRNA was equal in PiM cirrhotic and PiZZ cirrhotic (38.48 ± 4.5 vs. 31.93 ± 2.1), but significantly decreased from noncirrhotic PiM liver (58.36 ± 12.7). We conclude that α 1 ‐antitrypsin mRNA is decreased in cirrhosis of any etiology, and this decrease appears to represent a general response of the liver to injury. Since the decreased α 1 ‐antitrypsin mRNA in PiM cirrhotics is associated with normal serum α 1 ‐antitrypsin levels, it is unlikely that the decreased α 1 ‐antitrypsin mRNA in PiZZ cirrhotics accounts for their decreased serum levels.