Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Normal human neutrophils triggered by precipitating immune complexes (IC), soluble IC (sIC) or heat-aggregated IgG (HAIgG) displayed low levels of cytotoxicity towards nonsensitized target cells. Catalase, but not heated catalase, completely impaired this nonspecific cytotoxicity (NSC), suggesting a key role for hydrogen peroxide (H2O2) in the lysis of target cells. Superoxide dismutase (SOD) and certain HO. and 1O2 scavengers were unable to exert significant effects. Three haem-enzyme inhibitors, sodium azide, sodium cyanide and 3-amino-1,2,4-triazole did not decrease neutrophil NSC, but markedly enhanced it. This data suggest that the mechanism involved was not dependent upon myeloperoxidase (MPO). The analysis of neutrophil-mediated ADCC indicates that oxygen-dependent but MPO-independent mechanisms appeared to be operative in this system. It was also found that the microfilament disrupting agents, cytochalasin B (CB) and dihydrocytochalasin B (dhCB), as well as the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), significantly enhanced NSC. In contrast, these compounds partially inhibited ADCC. This cytotoxic system provides a suitable model to study events that may occur during the course of immune complex diseases and also permits the evaluation of alternative lytic mechanisms triggered through neutrophil Fc gamma receptors.
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PMID:Neutrophil-mediated cytotoxicity triggered by immune complexes: the role of reactive oxygen metabolites. 282 3

The role of toxic oxygen species in monocyte-mediated ADCC against the myelogenous cell line K-562 was investigated. Freshly isolated human monocytes caused 40% specific lysis of antibody-coated K-562 cells (Ab-K-562). Monocytes challenged with Ab-K-562 gave a small but definite luminol-dependent chemiluminescence response, indicating that a respiratory burst with generation of toxic oxygen species had been elicited. Generation of hydrogen peroxide in areas of close apposition between the monocyte and the Ab-K-562 plasma membranes was demonstrated by electron microscopy using precipitation of cerium ions as a cytochemical stain for hydrogen peroxide. Catalase inhibited the formation of cerium precipitates in the interaction zone between monocytes and Ab-K-562 cells. Despite evidence that toxic oxygen species were generated, the monocytes' cytolytic activity against Ab-K-562 was not inhibited by superoxide dismutase, catalase, or azide. Enzymatically generated fluxes of superoxide anion or hydrogen peroxide were not cytolytic to K-562 cells but did have a cytostatic effect. We conclude that toxic oxygen species are generated when human monocytes are challenged with Ab-K-562. However, these toxic oxygen species do not appear to be the major mediators of the monocytes' cytolytic activity in this experimental system.
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PMID:Toxic oxygen species in monocyte-mediated antibody-dependent cytotoxicity. 668 94