The role of mycobacteria and other bacterial adjuvants in modifying the hydrolase enzymes of phagocytes

Cater, Jerome Cagnet (1975) The role of mycobacteria and other bacterial adjuvants in modifying the hydrolase enzymes of phagocytes. PhD thesis, University of Glasgow.

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This thesis describes studies of the events which occur when macrophages are exposed to mycobacteria or anaerobic coryneform bacteria in vivo or in vitro. It chiefly explores two aspects of these events. Firstly, the ability of macrophages to digest and degrade these organisms; and secondly, the effect of the organisms on the activity of the acid hydrolases of the macrophages. The studies on the degradation of bacteria by macrophages were performed using as a model system, the response of the pulmonary alveolar macrophages of the chicken obtained either from normal chickens or from chickens pre-injected with M. avium upon incubation with various test organisms including M. avium, a pathogenic organism in birds. Mycobacterium tuberculosis is not pathogenic in birds but has a unique cell-wall structure which may determine its immunopotentiating effects. Various non-pathogenic mycobacteria, as well as the anaerobic coryneform bacteria, are also known to have important immunopotentiating effects. In contrast to these chronic granuloma forming organisms, the handling of Escherichia coli, a bacterium not usually regarded as granuloma-forming, by macrophages, was studied. The intracellular digestion studies showed, that stimulated macrophages from the chicken lungs, i.e. macrophages induced by prior injection of M. avium, digested the various acid-fast organisms when incubated with them in vitro much more rapidly than those from normal non-stimulated chickens; it also showed that the saprophytic strains of mycobacteria were degraded more rapidly than the pathogenic strains by chicken and mouse macrophages. As indicators of bacterial degradation, the disappearance of mycobacteria and/or a reduction in the number of stainable (acid-fast) organisms intracellularly in chicken lung macrophages was used. The stimulation of the activity of a number of lysosomal hydrolases, namely acid phosphatase, beta-glucuronidase, beta-galactosidase, alpha-mannosidase, cathepsin D, phospholipase A, and N-acetyl-beta-glucosamin-odase in the macrophages of the chicken lung by contact with various mycobacteria and coryneform bacteria was studied. It was shown that M, avium stimulated rises in the activity of these enzymes in vivo to a much greater extent than other mycobacteria and coryneform bacteria after inoculation intravenously into the chicken. This rise in the levels of the lysosomal enzymes in macrophages was shown to be related to the enhancement of intracellular degradation of microorganisms by these macrophages. It was shown that corynebacteria and mycobacteria caused selective release of mouse peritoneal macrophage lysosomal enzymes when incubated with these macrophages over a short time period in vitro. These organisms did not affect levels of the cytoplasmic enzymes, i.e. lactic acid dehydrogenase. In some experiments two inhibitors of protein synthesis were added before incubation to ascertain whether the effects observed were dependent on protein synthesis. The results showed that the enzymes released from mouse peritoneal macrophage in vitro on incubation with corynebacteria and mycobacteria were preformed enzymes and not newly synthesized. This result is in contrast to the results obtained in the chicken lung where activation of hydrolases was studied over a. long time period (three weeks) and where there is probably new synthesis of enzyme by macrophages. The accumulation of cells in the peritoneal cavity of mice, production of lysosomal enzymes by those cells and the presence of chemotactic factors in the peritoneal fluid were studied over a time period of three weeks following intraperitoneal injection of mycobacteria into mice, using as a control stimulant, glycogen which was injected into a second group of mice. These experiments showed that the levels of acid phosphatase, beta-glucuronidase and beta-galactosidase in mouse peritoneal macrophages rose as a result of injection of both mycobacteria and glycogen. Mycobacteria elicited a greater and longer sustained level of these enzymes and also elicited emigration of macrophages into the peritoneal cavity over a longer time period than glycogen. It was further shown in these experiments that intraperitoneal injections of mycobacteria or glycogen led to the formation of chemotactic factors for macrophages which presumably attract the cells into the peritoneum. Injection of mycobacteria led to a persistence of such factors in the peritoneal cavity over a longer time period than glycogen. The significance of these findings is discussed with reference to previously published work on the intracellular digestion of bacteria by macrophages, and on stimulation of lysosomal enzymes, and in the light of previous studies of the biological effects of the various strains of mycobacteria and coryneform bacteria.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: R G White
Keywords: Microbiology
Date of Award: 1975
Depositing User: Enlighten Team
Unique ID: glathesis:1975-72844
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06

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