Elastase is a potent proteolytic enzyme found within human neutrophil primary granules. Its major inhibitor in the serum is α1-antitrypsin, a protein that is synthesized by hepatocytes but which has recently also been shown to be synthesized by circulating neutrophils. The authors have therefore carried out an immunocytochemical study at the light microscopic and ultrastructural level to determine the intracellular localization of α1-antitrypsin. Double labeling with colloidal gold showed that α1-antitrypsin is localized at the same site as neutrophil elastase, i.e., within primary granules. Secondary granules (detected by labeling for lactoferrin) were unstained for α1-antitrypsin. Elastase and its major inhibitor therefore coexist within the same granule population within human neutrophils. Some difference in their intraorganelle distribution existed at the ultrastructural level (in that elastase tended to be localized at the periphery of the granules whereas α1-antitrypsin was usually diffusely present in the matrix of the granules), but further studies are required to determine whether the two molecules are already complexed with each other within the neutrophil.
|Number of pages||6|
|Journal||American Journal of Pathology|
|Publication status||Published - 1 Jan 1991|
ASJC Scopus subject areas
- Pathology and Forensic Medicine