Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heme-containing peroxidases have been demonstrated both biochemically and cytochemically in a variety of cells that either reside in the respiratory tract or circulate through it via the vasculature. The peroxidases in neutrophils and eosinophils have long been known to function in lung defense through their participation in an antimicrobial system involving hydrogen peroxide and chloride ions. Recent studies indicate that this system is also toxic to tumor cells and, as such, it may have a protective or mitigative effect on tumor formation in the lung. Eosinophil peroxidase may be involved in immediate hypersensitivity reactions in the lung because of its secretory effect on mast cells. Platelets contain peroxidases, but how they function is unknown. Whether peroxidase occurs in lymphocytes is controversial, but until more compelling evidence is presented they should be considered peroxidase-negative. A number of cells indigenous to the respiratory tract contain peroxidase activity, but there is considerable variability among species as to its presence and amount. When careful consideration is given to fixation and incubation conditions, peroxidase can be demonstrated cytochemically in the nuclear envelope and endoplasmic reticulum of some endothelial cells and type II cells of certain rodents, but its physiological role is speculative. The alveolar macrophages of most species possess little or no peroxidase activity apart from catalase which can function as a peroxidase under certain conditions. Mast cells in the respiratory tract contain peroxidase, but it is more easily demonstrated biochemically than cytochemically. The function of mast cell peroxidase is unknown, but two hypotheses worthy of investigation are its possible role in modulation of atopic allergic reactions and involvement in an antitumor defense mechanism similar to that of myeloperoxidase. Peroxidase is most abundant in the secretory cells of the tracheobronchial epithelium and glands where, in a number of species, it is synthesized and secreted as a component of mucus. Its possible contribution to lung defense is discussed in view of its morphologic similarity to the antibacterial peroxidase of milk and saliva. Because of the ease with which peroxidases can be demonstrated cytochemically, it is not surprising that morphologic information regarding their distribution in the respiratory tract has greatly exceeded insights into their functional significance. It is hoped that advancements in cell dissociation and culture, along with biochemical isolation and purification techniques, will lead to definitive conclusions concerning their physiologic roles in lung metabolism and defense.
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PMID:The distribution and function of peroxidases in the respiratory tract. 638 50

It has been previously demonstrated that eosinophil peroxidase (EPO) when supplemented with hydrogen peroxide and a halide induces noncytotoxic mast cell degranulation. Using a more highly purified EPO preparation, the ultrastructure of EPO-induced mast cell secretion has been studied using transmission and scanning electron microscopy and freeze-fracture techniques. At relatively low EPO concentrations, secretory changes were comparable to those caused by other mast cell secretagogues. Swollen and less electron-dense granules were seen in intracellular channels, some of which opened to the outside of the cell. EPO stimulation led to bulging of the surface membrane by submembranous granules and formation of pores in the cell surface that also contained fewer villous projections than control cells. During the secretory process, plasma membrane bulges were depleted of intramembranous particles in both the E and P faces of the apical regions of the perigranular and plasma membranes. Higher EPO concentrations caused a marked cytotoxic disruption of the mast cells. Diaminobenzidine cytochemistry was used to detect EPO reaction products on the mast cell surface by scanning electron microscopy; this technique should prove useful in detecting peroxidase reaction products on a variety of target cells.
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PMID:Ultrastructure of mast cell degranulation induced by eosinophil peroxidase: Use of diaminobenzidine cytochemistry by scanning electron microscopy. 642 Apr 61

The present studies were initiated to study peroxidase and its possible regulation by estrogen in normal mammary glands. The activity of peroxidase was measured biochemically using guaiacol as the substrate for oxidation. Significant levels of peroxidase activity were associated with the particulate fraction of mammary glands from virgin mice, pregnant mice, and mice undergoing lactational involution. However, during lactation there was no detectable level of peroxidase activity in the mammary glands. Although ovariectomy led to a decrease in mammary peroxidase, detailed studies using various hormonal manipulations revealed that mammary peroxidase was perhaps not a product of estrogen action alone, but might be the result of a complex hormonal control related to growth. Alternatively, a critical evaluation of all of the data obtained with mammary glands and a comparison of these data obtained with the uterus also suggest that the presence of peroxidase in mammary glands may be due to infiltration of eosinophils and macrophages in these tissues resulting from mast cell degranulation.
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PMID:An evaluation of peroxidase as a marker for estrogen action in normal mammary glands of mice. 664 32

Eosinophil peroxidase (EPO) and to a lesser degree neutrophil peroxidase (myeloperoxidase, MPO) bound tightly to mast cell granules (MCG), particularly when the latter were depleted of histamine by suspension in physiologic salt solutions. The bound EPO was localized on the surface of the granule, and its dissociation required salt concentrations of high enough ionic strength (greater than 0.75 M) to solubilize the MCG matrix. Elution of MPO from the complex occurred at a lower salt concentration. The MCG/EPO complex retained the capacity of the isolated EPO to catalyze the iodination reaction when supplemented with iodide, H2O2, and a protein acceptor and to kill microorganisms when supplemented with H2O2 and a halide (iodide, chloride). Indeed, the MCG/EPO complex had significantly greater iodinating and bactericidal activity than the free enzyme when standardized to equal guaiacol units of peroxidase activity. Thus, in areas of inflammation where mast cells and phagocytic leukocytes coexist, there is the potential for the formation of active complexes extracellularly between mast cell granules and molecules such as EPO (or MPO) that can affect the inflammatory response.
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PMID:Binding of eosinophil peroxidase to mast cell granules with retention of peroxidatic activity. 698 10

The phagocytosis by mononuclear phagocytes, neutrophils and eosinophils of mast cell granules which are released in the course of anaphylactic reactions was studied in the rat. Degranulation of rat peritoneal mast cells was induced either in vivo or in vitro after passive sensitization with homologous reaginic antiovalbumin serum by challenge with the antigen. The approximate extent of degranulation was assessed by determining histamine release. The anaphylactic reaction was stopped by fixation with glutaraldehyde and the cells were examined by electron microscopy. Phagocytosis was quantified in randomly selected thin section at the magnification of 1,800. Rapid and extensive phagocytosis of mast cell granules was observed both in vivo and in vitro. About one third of the mononuclear phagocytes and between 30 and 53% of the neutrophils present were engaged in phagocytosis and usually contained several mast cell granules. Phagocytosis by eosinophils was less prominent, both with respect to the proportion of phagocytosing cell (10-23%) and to the number of mast cell granules per cell profile. Examination of large numbers of cells indicates that the uptake process is highly efficient since both condensed and already disaggregated granule bodies were seen to adhere to the phagocytes and were taken up rapidly and without the need for opsonization. In the neutrophils, extensive fusion of azurophil granules (as evidenced by peroxidase cytochemistry) with phagosomes containing mast cell granules was observed. Occasionally, mast cell granules were seen within disrupted vacuoles, which could result from the swelling of the granule matrix following engulfment. The result of this study indicate that mononuclear and polymorphonuclear phagocytes have the capacity to scavenge important amounts of mast cell granule products released by anaphylaxis.
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PMID:Phagocytosis of mast cell granules by mononuclear phagocytes, neutrophils and eosinophils during anaphylaxis. 706 Nov 53

Mast cells, when supplemented with H2O2 and iodide, are cytotoxic to mammalian tumor cells as determined by 51Cr release, and transmission and scanning electron microscopy. H2O2 at the concentration employed (10(-4) M) initiates mast cell degranulation, and mast cell granules (MCG), which contain a small amount of endogenous peroxidase activity, are toxic to tumor cells when combined with H2O2 and iodide. This toxicity is greatly increased by binding eosinophil peroxidase (EPO) to the MCG surface. Each component of the mast cell, MCG, or MCG-EPO system was required and toxicity was inhibited by the addition of the hemeprotein inhibitors azide or aminotriazole, which is compatible with a requirement for peroxidase in the cytotoxic reaction. A sequence of reactions is proposed in which mast cells, stimulated to release their granules by H2O2 generated by adjacent phagocytes, react with H2O2 and a halide to damage tumor cells. EPO release from eosinophils may contribute to this sequence of reactions, both by stimulation of H2O2-induced mast cell secretion and by combination with MCG to form a complex with augmented tumoricidal activity. These rections may play a role in the host defense against neoplasms.
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PMID:Mast cell-mediated tumor-cell cytotoxicity. Role of the peroxidase system. 725 7

Soft agar culture of mononuclear cell fractions prepared from rat peripheral blood yielded numerous colonies consisting of mast cells. The mast cell nature of the cells was established by ultrastructural and histochemical analyses as well as by the demonstration the the colonies contained histamine and that the cells possessed receptors for the Fc component of IgE. Stringent criteria for the distinction of mast cells from monocytes/macrophages that could have metachromatic inclusions were applied. The alcian-blue-safranin technique delineated the maturation of mast cell granules by showing the loss of alcian-blue and increase in safranin-positive organelles presumed to reflect the increase in N-sulfated polysaccharides representing heparin. The mast cells exhibited low or absent reactions for peroxidase, alpha-naphthyl butyrate, periodic acid Schiff, and Sudan black reacting lipid, whereas macrophages stained in parallel were positive for these substances. Since it is known that extracellular conditions may cause variations in phenotypic expression, the observations have led to the hypothesis that mast cells and macrophages may have a common precursor.
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PMID:The presence of mast cell precursors in rat peripheral blood. 725 36

Human LDLs oxidized with Cu2+ are known to promote leukocyte-endothelial cell adhesion (LECA) and albumin leakage in postcapillary venules. The objective of this study was to compare the ability of LDL oxidized with Cu2+ (Cu-LDL), phospholipase A2 plus lipoxygenase (PLA2-LDL), horseradish peroxidase plus H2O2 (HRP-LDL), or -OCl (-OCl-LDL) to promote (1)neutrophil-endothelial cell adhesion (NECA) in vitro and (2)LECA and albumin leakage in rat mesenteric venules. In vitro adhesion assays revealed that only Cu-LDL elicited a dose-dependent NECA response, whereas PLA2-LDL but not normal (N-LDL), HRP-LDL, or -OCl-LDL increased NECA at the highest concentration studied (670 micrograms/mL). The magnitude of the NECA responses elicited by the different forms of oxidized LDL was related to the degree of lipid peroxidation but unrelated to the level of protein oxidation. Local intra-arterial infusion of Cu-LDL, PLA2-LDL, or -OCl-LDL but not N-LDL elicited significant increases in leukocyte adherence and emigration, mast cell degranulation, and albumin leakage in rat mesenteric venules. The LECA induced by all forms of oxidized LDL was not accompanied by significant alterations of venular shear rate.
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PMID:Oxidized LDL-induced microvascular dysfunction. Dependence on oxidation procedure. 748 57

Endogenous peroxidase has been reported in rat peritoneal mast cells and granules. Mast cell granules have also been shown to avidly bind exogenous eosinophil peroxidase. To examine the possibility that contaminating eosinophil peroxidase contributes to the reported rat mast cell peroxidase activity, mast cells were increasingly purified over sequential Percoll gradients. Such repeated centrifugations did not affect the histamine content of the cells or the secretory activity of cells, but the small increases in mast cell purity significantly reduced the specific activity of peroxidase; the remaining peroxidase activity of the mast cell fraction was in a range that could easily be accounted for by a small extent of contamination with eosinophils. An upper limit of 0.3 ng peroxidase/10(6) mast cells was determined from these measurements, ten times less than the values previously reported. When isolated mast cells were deliberately contaminated with soluble eosinophil peroxidase followed by granule isolation, the granules showed increased peroxidase activity, confirming the ability of mast cell granules to bind exogenous peroxidase.
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PMID:Eosinophil peroxidase accounts for most if not all of the peroxidase activity associated with isolated rat peritoneal mast cells. 751 May 60

Twelve histochemical methods; affinity staining with avidin peroxidase, wheat germ agglutinin, and concavalin-A agglutinin; and an immunohistochemical stain with Kp1 (CD68) antibody were compared for their relative effectiveness in staining canine mast cell tumors. Stains were compared in 28 mast cell tumors and 19 histiocytomas. The effectiveness of the histochemical methods and the lectins decreased as the mast cells became less differentiated. None of the staining methods were positive on histiocytomas. Periodic acid-Schiff (PAS) gave positive results in a few cases of mast cell tumors where other histochemical stains were negative. Although avidin peroxidase and Kp1 antibody stained more mast cell tumors than any other method, they did not differ significantly from Luna's method, toluidine blue pH 0.5, toluidine blue pH 4.5, alcian blue pH 2.5, safranin O, Unna's method, and Giemsa. No stain was ideal for the diagnosis of canine mast cell tumors; however, this study suggests that the use of avidin peroxidase, Kp1 antibody, and PAS may give additional information for individual poorly differentiated tumors without substantial increase in time or cost.
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PMID:Canine mast cell tumors: a comparison of staining techniques. 753 14


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