Alpha 1-antitrypsin variants produced by recombinant DNA: differences in elastase inhibitory activity and resistance to oxidant agents

Inherited or "acquired" deficiency of alpha 1-antitrypsin (believed to be the cause of pulmonary emphysema) will probably be treated in the future by replacement with alpha 1-antitrypsin purified from human plasma or produced by recombinant DNA, which seems promising because it permits site-specific mutagenesis in the oxidizable active site of the normal human alpha 1-antitrypsin. The aim of this in-vitro study was to investigate the elastase inhibitory activity and the resistance to oxidizing agents of normal human alpha 1-antitrypsin, a recombinant yeast-produced variant (VAL 358) and a recombinant E. coli-produced variant (LEU 358). The inhibitors were exposed to chemical oxidants (NCS, H2O2, xanthine/xanthine oxidase, chloramine-T) and to PMA-activated neutrophils. The elastase inhibitory activity was assayed on porcine pancreatic elastase and neutrophil elastase. Normal alpha 1-antitrypsin and VAL 358 variant were good inhibitors of both elastases. LEU 358 variant was the best inhibitor for neutrophil elastase, but it poorly inhibited the porcine pancreatic elastase. Normal alpha 1-antitrypsin was affected by all oxidants; both variants were almost totally resistant to chemical oxidants and to activated neutrophils. We conclude that recombinant alpha 1-antitrypsin variants differ in their elastase inhibitory activity and offer increased resistance to oxidant agents.