PRODUCTION OF RECOMBINANT HUMAN MONOCYTE NEUTROPHIL ELASTASE INHIBITOR (RM NEI)/

Recombinant human monocyte/neutrophil elastase inhibitor (rM/NEI) was expressed with a baculovirus expression system. The purified recombina nt protein was shown to inhibit human neutrophil elastase by the forma tion of a stable equimolar complex, as had been shown for M/NEI isolat ed from monocyte-derived cell lines. rM/NEI was remarkably stable in a queous buffers from pH 6 to pH 8, but not in buffers below pH 6. rM/NE I activity was stable when subjected to freeze-thaw cycles and low tem perature storage in Tris or phosphate buffers, rM/NEI could also be ly ophilized without significant loss of activity. A 1.6-g batch of great er than 95% purity in rM/NEI was obtained by anion exchange and size e xclusion chromatography with yields of 7 to 8 mg per liter of cultured insect cells. Methods and protocols were chosen for compatibility wit h large-scale cGMP production and were suitable for biochemical charac terization and preclinical evaluation of rM/NEI as a therapeutic agent for cystic fibrosis. The availability of large amounts of purified rM /NEI will facilitate clinical evaluation of rM/NEI for prevention of t he elastase-mediated destruction of lung tissue associated with the mo rbidity and mortality of cystic fibrosis. (C) 1998 Academic Press.