Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this report, we present data on the activation of different neutrophil effector functions by two distinct Fc-gamma receptors, FcRII and FcRIII. We and others have shown previously that IgG-dependent activation of phagocytosis and superoxide generation is mediated via FcRII. IgG-dependent exocytosis of granule proteins was assessed with Staphylococcus aureus Oxford opsonized with human IgG or with IgG-coated latex. Both anti-FcRII mAb and anti-FcRIII-F(ab')2 mAb inhibited this release, whereas the combination of these mAb inhibited this process more strongly than either mAb alone. This indicates that both FcRII and FcRIII are involved in IgG-dependent release of granule proteins. Cross-linking of the receptors by anti-FcR mAb and F(ab')2 fragments of goat-anti-mouse-Ig showed again that both FcRII and FcRIII mediate lysozyme release, whereas cross-linking of a control antigen (CD67) did not. By measuring the release of elastase and lactoferrin, we found that cross-linking of either FcRII or FcRIII induced release of both azurophilic and specific granules. Under these conditions, we did not measure any activation of the respiratory burst. When FcRIII was removed by treatment of neutrophils with glycosylphosphatidylinositol-specific phospholipase C, the lysozyme release induced by cross-linking of FcRIII was lower than the release from control neutrophils, whereas the release induced by cross-linking of FcRII was similar. Therefore, we conclude that IgG-dependent activation of neutrophils follows two distinct pathways: one via transmembrane FcRII, activating both the NADPH oxidase and the release of granule proteins (as was demonstrated previously by us and by others), and the other via phosphatidylinositol-linked FcRIII, activating exocytosis of granule proteins.
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PMID:Phosphatidylinositol-linked FcRIII mediates exocytosis of neutrophil granule proteins, but does not mediate initiation of the respiratory burst. 213 91

N-acetylmuramyl-L-alanine amidase (NAMLAA) specifically degrades peptidoglycan, a major component of bacterial cell walls. Lysozyme degrades peptidoglycan differently by hydrolyzing the aminosugar backbone of peptidoglycan. In another study, it was shown that the two enzymes act synergistically to inactivate the inflammatory properties of peptidoglycan. The presence of lysozyme and NAMLAA was determined in serum and cerebrospinal fluid (CSF) of patients with bacterial meningitis. High concentrations of lysozyme were found in CSF while, surprisingly, NAMLAA was not present. To explain this phenomenon, the degranulation pattern of neutrophils in CSF was compared with that of neutrophils from blood. Specific granules contain lysozyme and the azurophil granules contain both lysozyme and NAMLAA. CD66b expression on the cell surface, indicative for fusion of the specific granules with the cell membrane, was higher in CSF than in blood, while the marker for the azurophil granules was lower.
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PMID:Differences in N-acetylmuramyl-L-alanine amidase and lysozyme in serum and cerebrospinal fluid of patients with bacterial meningitis. 941 76