Biomedical subjects
Publications and source records attributed to D M Weir.
Human monocytes show an increased ability to bind pilate rather than non-pilate gonococci. Polymorphonuclear leucocytes (PMN) do not discriminate between pilate and non-pilate variants. PMN, however, bind appreciably more gonococci (either pilate or non-pilate) than monocytes. The results help to explain the role of pili on gonococci as virulence factors and in the immune response.
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Mice made diabetic by treatment with alloxan showed increased susceptibility to intraperitoneal injection of a rough strain of Salmonella typhimurium (SL 1099) expressing glucose as the terminal sugar of its core lipopolysaccharide. Peritoneal exudate cells from mice with alloxan induced diabetes were compared with those from control mice for binding and uptake of S. typhimurium. Cells from the diabetic mice bound fewer bacteria than those of non-diabetic mice. The implications of these findings are considered in relation to bacterial pathogenicity in diabetes.
A mannose specific lectin has been isolated by affinity chromatography from the cell wall of C. parvum. Polyacrylamide gel electrophoresis indicates that the lectin molecules lie in the molecular weight range 57,000--72,000. It appears that C. parvum like E. coli and salmonellae express lectins that bind to cells expressing mannose in their membranes. This may partly account for the interaction between C. parvum and the macrophage leading to the various immunological phenomena associated with C. parvum administration.
Lectin-like receptors capable of binding the bacterium Staphylococcus albus have been demonstrated in the membranes of phagocytes including macrophages, neutrophils and eosinophils from various sources and species. Such receptors are likely to contribute to bacterial adherence and phagocytosis in the non-immune animal.
Antigenic specificities of native monomer, heat-denatured monomer and heat-polymerized BSA have been compared serologically. Distinct differences between monomer and polymer preparations were observed with respect to their ability to inhibit each other's binding to antibody and also between their respective rates of dissociation from immune complexes. While it would be possible to interpret the results in terms of the appearance of 'new' antigenic determinants on the polymerized antigen, the results are best explained by an enhanced capacity of polymerized BSA to establish polyvalent binding to antibody of low intrinsic affinity.
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A binding interaction is described between mouse peritoneal macrophages, tumour cells and proliferating mouse embryo fibroblasts. The interaction appears to be between a "lectin-like" receptor in the macrophage plasma membrane and carbohydrates in the plasma membrane of the target cells.
The recognition by macrophages of unopsonized bacteria was studied, employing a binding assay, performed at 4 degrees C. Various Gram positive and Gram negative bacteria were shown to bind to glass-adherent mouse peritoneal exudate cells under these conditions, Str. pneumoniae being the only exception. The binding could be inhibited by pretreatment of the macrophage monolayers with various monosaccharides. The role of particular components of the bacterial cell wall in binding was examined further using different strains of K. aerogenes and S. typhimurium with a known cell wall composition and mutant strains deficient in certain sugars. The ability of a particular constituent to inhibit binding was found to correlate closely with its presence in the bacterial cell wall. It is concluded, that this form of binding, mediated by cell wall carbohydrates represents a primitive recognition mechanism enabling phagocytes to bind microorganisms.
The nature of the binding of C. parvum organisms to the surface of glass-adherent mouse peritoneal exudate cells in vitro was studied using pretreatment of the cells with various enzymes and periodate. Trypsin, pronase, beta-galactosidase, phospholipases A, C and D and periodate all caused a decrease in binding to 40-60% of untreated control. Neuraminidase led to a 30% increase in binding. The binding ability returned to normal after 1 h at 37 degrees in culture medium following exposure to all the enzymes apart from pronase, which apparently could not be removed effectively by washing. The presence of EDTA in the medium inhibited recovery from treatment with trypsin and beta-galactosidase; return to normal after exposure to phospholipases A, C and D was slightly affected, whereas recovery from treatment with neuraminidase was unaffected. Cells that had been exposed to periodate did not regain normal binding ability after 1 h in tissue culture medium but the effect could be reversed chemically by treatment with borohydride. The role of different plasma membrane components in non-specific cellular recognition is discussed.
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Corynebacterium parvum, strain 10390, whole organisms were shown to bind to the surface of glass-adherent mouse peritoneal exudate cells in vitro. An HCl extract and a lipid extract of the organism were both capable of inhibiting this binding. The attachment of organisms was not affected by trypsin treatment of the cells, indicating that the plasma membrane receptor is not cell-bound antibody in nature. The binding was inhibited by various sugars, most of which are major components of the cell wall of C. parvum. Removal of divalent cations prevented binding. At room temperature some binding occurred in the presence of magnesium ions alone, whereas both calcium and magnesium ions were required at 4 degrees C. The possibility is discussed that the attachment of C. parvum to the plasma membrane of macrophages may lead directly to their activation.
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The immunological adjuvant Corynebacterium parvum has been to activate the alternate pathway of complement in human and guinea-pig serum. Human serum in addition contains anti-C. parvum antibodies leading to activation of the classical complement pathway. The possible role of a C. parvum derived polysaccharide in this activation is considered in relation to the biological effects of the micro-organism.
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Explore the source record for details and available documents.