Subcellular localization and heterogeneity of neutral proteases in neutrophilic polymorphonuclear leukocytes.

Abstract

The subcellular localization of elastase and of neutral proteases hydrolyzing histone and casein was determined in human and rabbit polymorphonuclear leukocytes using fractionation by isopycnic centrifugation. Granule-rich fractions obtained by this technique were extracted and analyzed by acrylamide gel electrophoresis, and proteolytic activity on the gels was demonstrated by staining with either N-acetyl-D,L-alanine alpha-naphthyl ester or naphthol AS-D acetate as substrate. In both species, all neutral proteases assayed were found to be localized exclusively in the azurophil granules. Specific activities were about 10-30 times higher in human than in rabbit preparations. In extracts of human azurophil granules up to 10 proteins exhibiting esterolytic activity could be demonstrated after electrophoretic separation. Three major and two or three minor components of these esterases were shown to possess elastase activity. Similar zymograms prepared with extracts from rabbit azurophil granules revealed only one major elastase band. The electrophoretic analysis further showed that the most strongly cationic proteins of both human and rabbit PMNs were also confined to the azurophil granules.

Neutral protease secretion by human monocytes. Effect of surface-bound immune complexes.

“…Intracellular deiodination may be due to the activity of myeloperoxidase (36), which is found in the azurophilic granules of both monocytes and PMN (37,38). Under certain conditions, myeloperoxidase may be active in the extracellular environment (36) although the site of deiodination in our experiments was not elucidated.…”

Antibacterial activity of cationic proteins from human granulocytes.

“…The cationic proteins of rabbit polymorphonuclear leukocytes are associated with the peroxidase-containing granules (32). Electrophoretic analysis carried out by Dewald et al (34) on granule fractions obtained by isopycnic centrifugation showed that the most strongly cationic proteins of both human and rabbit granulocytes were confined to the azurophil granules. Recently we have shown the chymotrypsin-like cationic proteins of this study to be localized exclusively in the azurophil granules.'…”

Polymorphonuclear neutrophils release 35S‐labelled proteoglycans into cartilage during frustrated phagocytosis

“…la) and of P-glucuronidase and elastase activity (Fig. 1b) in the sucrose gradient; 34% of the label from a post-mitochondria1 supernatant was associated with the azurophil granule fraction (peak I) which was enriched with elastase activity (Dewald et al, 1975), 8% with the specific granule fraction (peak 11) which was detected as a peak of p-glucuronidase activity while 58% remained at the top of the gradient (peak 111) and probably comprised the soluble fraction. The labelled macromolecules from each of these three fractions were extracted with 4.0 M guanidinium chloride and subjected to ion-exchange chromatography on DEAE-Sephacel in 6 M urea.…”