title: The release of lysosomal enzymes from human polymorphonuclear leukocytes by human C3e.
abstract: C3e is a leukocytosis-inducing peptide of degraded C3 that has the electrophoretic behavior of prealbumin and a MW of 10-12,000. Using a homogeneous preparation, the ability of C3e to promote lysosomal enzyme release from human polymorphonuclear leukocytes (PMNs) was examined by incubation of various concentrations of C3e with cytochalasin B-treated (5 micrograms/ml) human PMNs for 60 min at 37 degrees C. Amounts of extracellular beta-glucuronidase, myeloperoxidase, and lysozyme were determined in the cell-free supernatants and it was found that all three enzymes were released in significant amounts without concomitant release of the cytoplasmic enzyme lactate dehydrogenase (LDH). At a concentration of 25 micrograms/ml of C3e, 25 +/- 1.1% (SD) of lysozyme, 20 +/- 0.9% beta-glucuronidase, and 24.3 +/- 0.9% myeloperoxidase were released into the supernatant while the release of LDH remained within the 4-7% range throughout these studies. Furthermore the supernatants were found to contain a substance which was capable of a generating chemotactic fragment from isolated C5. The same range of C3e concentrations (5-25 micrograms/ml) was, however, incapable of effecting histamine release from basophils. These results suggest that generation of C3e in vivo may serve as a potent stimulus for the generation of the C5-cleaving enzyme from PMNs which in turn may function to recruit more neutrophils by a positive feedback mechanism.
mesh_terms: D001491:Basophils / Q000276:immunology; D002634:Chemotaxis, Leukocyte; D003176:Complement C3 / Q000378:metabolism / Q000502:physiology*; D003179:Complement C3b; D004306:Dose-Response Relationship, Immunologic; D006636:Histamine Release; D006801:Humans; D008247:Lysosomes / Q000201:enzymology*; D016177:Macrophage-1 Antigen; D009504:Neutrophils / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism; D010446:Peptide Fragments / Q000502:physiology*; D011951:Receptors, Complement / Q000378:metabolism
chemical_list: D003176:Complement C3; D016177:Macrophage-1 Antigen; D010446:Peptide Fragments; D011951:Receptors, Complement; C040268:complement C3e; D003179:Complement C3b