Showing papers on "Myeloperoxidase published in 1972"

Functional Aspects of a Second Mechanism of Candidacidal Activity by Human Neutrophils

Abstract: We tested the ability of human neutrophils to kill five Candida species and the yeast Torulopsis glabrata. C. parapsilosis and C. pseudotropicalis were found to be killed readily by normal and myeloperoxidase-deficient neutrophils and were selected to probe the myeloperoxidase-independent fungicidal mechanisms of the neutrophil. These organisms were killed with relatively normal (C. parapsilosis) or moderately reduced (C. pseudotropicalis) effectiveness by neutrophils from two boys with X-linked chronic granulomatous disease. Azide (2 mm) and sulfadiazine (4 mm) exerted a relatively small inhibitory effect on the ability of normal neutrophils to kill C. parapsilosis. These compounds did not, however, inhibit the killing of C. parapsilosis by myeloperoxidase-deficient neutrophils, although they blocked their iodination of ingested Candida cells. Anaerobic incubation conditions inhibited the ability of normal neutrophils to kill C. parapsilosis slightly but did not impair this function in myeloperoxidase-deficient cells. All of the Candida species tested had catalase activity, yet their sensitivity to H(2)O(2) in cell-free systems varied considerably. Our C. parapsilosis strain was extraordinarily resistant to H(2)O(2) (LD(75): 0.14 m), as compared with C. pseudotropicalis or with our reference strain of C. albicans (LD(75): 2.3 x 10(-3)m and 3.4 x 10(-3)m, respectively). These data establish the existence in human neutrophils of a second mechanism that exerts microbicidal activity against certain Candida species; the mechanism is unrelated to myeloperoxidase, iodination, or to the direct effects of H(2)O(2) generated by the endogenous metabolic processes of the neutrophil. As yet unidentified, this mechanism appears to remain operative in the neutrophils of subjects with hereditary myeloperoxidase deficiency or chronic granulomatous disease.

Microbicidal activity of peroxidaseless chicken heterophile leukocytes.

Abstract: Polymorphonuclear leukocytes (PMN) of the domestic chicken lack myeloperoxidase and, therefore, may be useful for studies of myeloperoxidase-independent antimicrobial mechanisms. Before such studies were undertaken, it was important to investigate the antimicrobial capacity of these cells against species of opportunistic pathogens that cause infection in humans with defective PMN function. In vitro, chicken PMN, like normal human PMN, readily phagocytized and killed Staphylococcus albus. They also killed Serratia marcescens, Escherichia coli, and Candida albicans. Cytochemical methods confirmed the absence of myeloperoxidase from chicken PMN.

Biological effects of hypochlorous acid formed by “mpo”-peroxidation in the presence of chloride ions

Abstract: Publisher Summary This chapter elaborates about biological effects of hypochlorous acid formed by myeloperoxidase (MPO). MPO is enclosed in the peroxidase positive granules within the cytoplasm of the polymorphnuclear, neutrophilic leucocytes—also termed myelocytes—in a high concentration. It has been considered important to evaluate the possibility whether MPO would be engaged in the formation of any chemically defined agent, which by a direct action upon, or after a reaction with, plasma proteins or leucocyte cell constituents can transform them into products, which thereafter can produce alexin and leukin activities upon some of the metabolizing activators within the bacterial cells and by such preliminaries prepare them for a final lysis by phagocytosis. Bacteria suspended in saline or in serum added with chloro-quinone-diimines were killed. The germicidal effect upon bacteria suspended in serum required a higher concentration than the one sufficient for the same effect upon the bacteria suspended in saline.

Refractory Megaloblastic Anemia with Myeloperoxidase-Deficient Neutrophils

Abstract: The enzyme myeloperoxidase contributes to the ability of human leukocytes to kill fungi and bacteria We studied a 61-year-old man with megaloblastic anemia and two populations of neutroph

The Function of the Phagocytic Leucocytes in Leukaemia

Abstract: Summary. Various aspects of the function of the phagocytic cells (neutrophils and monocytes) in the peripheral blood of patients with leukaemia have been reviewed. Mobilization of neutrophils and monocytes to sites of experimentally induced inflammatory lesions appears to be defective in acute myeloid leukaemia (AML). Phagocytosis (uptake of bacteria) appears to be defective in the neutrophils of patients with untreated chronic granulocytic leukaemia. The killing of Candida albicans by neutrophils from patients with AML also seems to be impaired. Preliminary evidence suggests that monocytes from patients with acute monocytic leukaemia have an enhanced phagocytic and candidacidal activity after 7 days in culture. Neutrophils and monocytes from patients with AML do not differ from normal leucocytes in their capacity to reduce nitroblue tetrazolium which suggests that cellular metabolism after phagocytosis is not greatly disordered in leukaemic cells: however, a possible deficiency in the neutrophils in chronic granulocytic leukaemia is suggested. On the other hand, some leukaemic neutrophils lack the enzyme myeloperoxidase and this abnormality is particularly associated with the myeloblastic-promyelocytic type of AML. The contribution of these leucocyte abnormalities to the pathogenesis of infection is discussed.

Mouse Splenic Peroxidase and Its Role in Bactericidal Activity

Abstract: Spleen cell suspensions from AKR and CD-1 mice contain peroxidase activity as determined by guaiacol oxidation. This activity is found predominately in the 20,000 x g pellet fraction of spleen cell homogenates. In the presence of H(2)O(2) and chloride ion at acidic pH, splenic peroxidase mediates the oxidation of d- or l-alanine to CO(2), NH(3), and acetaldehyde. The same reaction mixture without added amino acid can kill both gram-positive and gram-negative bacteria. The conditions for both reactions are similar. Both have an absolute requirement for H(2)O(2) and chloride ion, neither is active at neutral or alkaline pH, and both are inhibited by the sulfonic amino acid taurine. In these aspects, splenic peroxidase is qualitatively similar in its activity to myeloperoxidase (MPO) from polymorphonuclear leukocytes. It is quantitatively different from MPO in that the latter is more potent on a per guaiacol unit basis with respect to both amino acid oxidation and bactericidal activity. Still another quantitative difference is that splenic peroxidase requires 0.1 m NaCl for activity, whereas MPO functions with as little as 0.005 m NaCl. Splenic peroxidase and MPO both appear to differ qualitatively from horseradish peroxidase in that the latter enzyme does not mediate amino acid oxidation.