To evaluate the potential use of recombinant DNA-produced α-1-antitrypsin (α-1-AT) to augment the lung antineutrophil elastase defenses in α-1-AT deficiency, we compared the kinetics of intravenously administered recombinant produced α-1-AT (rα-1-AT) and purified normal human plasma α-1-AT (pα-1-AT) in the blood and lung of rhesus monkeys. The rα-1-AT was produced in yeast transformed with an expressing plasmid containing a full-length human α-1-AT complementary deoxyribonucleic acid and purified to > 99% homogeneity. The rα-1-AT has a molecular weight of 45,000, no carbohydrates, and is identical in sequence to normal plasma α-1-AT except for an additional N-terminal acetylmethionine. Despite its lack of carbohydrates, the rα-1-AT inhibited human neutrophil elastase with an association rate constant similar to that of pα-1-AT. Rhesus monkeys were infused intravenously with 120 mg/kg of rα-1-AT (n = 13) or pα-1-AT (n = 12) and the serum, urine, and lung epithelial lining fluid (ELF) concentrations of these molecules quantified at various intervals. Although the initial serum levels of the rα-1-AT and pα-1-AT were both dose dependent, the pα-1-AT remained in the blood for at least 4 days, whereas the rα-1-AT disappared rapidly, such that it was barely detectable at 24 h and strikingly, although no pα-1-AT was detectable in the urine at any time, 38% of the intravenously administered rα-1-AT was excreted within 3 h. Similar to its behavior in humans, the pα-1-AT diffused into the lung such that its concentration in the ELF of the lower respiratory tract 1-4 days after infusion was ~ 10% that in serum. Interestingly, the rα-1-AT molecule also diffused into the lung, with ELF levels at 24 h similar to that of the pα-1-AT. Furthermore, although the rα-1-AT ELF levels declined by 48 and 96 h to below those of the pα-1-AT ELF levels, the rα-1-AT ELF levels exceeded those in blood at the same time points and, like the pα-1-AT, resulted in a significant augmentation of the antineutrophil elastase capacity of the ELF. Thus, in primates, human-based rα-1-AT has very different pharmacokinetics than does human pα-1-AT, likely because of its modified charge and/or conformation. Despite this, however, the rα-1-AT does diffuse into the lung and augment the antineutrophil elastase capacity of the ELF of the lower respiratory tract, suggesting that it has potential as a therapeutic agent in the treatment of disorders such as α-1-AT deficiency.
|Number of pages||9|
|Journal||Journal of Applied Physiology|
|Publication status||Published - 1 Dec 1987|
ASJC Scopus subject areas
- Physiology (medical)