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Biomedical subjects

S Norn

Publications and source records attributed to S Norn.

At least 19 recordsLinked to original sources

[Respiratory tract infection and acute deterioration of obstructive lung disease].

Respiratory infection may aggravate chronic obstructive pulmonary disease. Viral respiratory infections may aggravate asthma, particularly in young individuals. Respiratory Syncytial virus and Rhinovirus dominate in children while, in adults, Influenza or Rhinovirus infections are most frequently concerned. Viral respiratory infections may also cause exacerbation of chronic bronchitis. Bacteria and their products scarcely play any part in asthmatic disease but may possibly aggravate chronic bronchitis and other forms of obstructive respiratory disease. In particular, Haemophilus influenzae and Streptococcus pneumoniae and bacterial endotoxin appear to be of significance. The mechanisms of the effects of viruses have several points of attack: Destruction of epithelium, release of mediators, potentiation of mediator-release and reduced beta-adrenergic function. Bacteria and their products may, similarly, cause bronchoconstriction and may, in vitro, release mediators and potentiate release of mediators.

Bacterial Infections

Bacteria-induced histamine release from human bronchoalveolar cells and blood leukocytes.

Histamine release induced by Staphylococcus aureus was examined in cells obtained by bronchoalveolar lavage (BAL) in non-atopic individuals. Approximately half of the individuals responded with mediator release to the bacterium, and the release was found to be time- and concentration dependent. No difference was found between the patients who responded and those who did not respond in regard to age, sex, smoker/non-smoker, % recovery of BAL-fluid, total cell count, differential cell counts, histamine content per mast cell, or diagnoses. Also stimulation of the BAL-cells with the calcium-ionophore A23187 resulted in histamine release. S. aureus-induced histamine release from basophils was examined in leukocyte suspensions obtained from the same individuals, and in all experiments release was found. The dose-response curves were similar to those obtained with BAL cells. The bacteria-induced mediator release from superficially lying cells in the airways epithelium might be of importance for the precipitation or exacerbation of bronchial asthma in respiratory tract infections.

Adult

Cytokine-induced histamine release from basophils of AIDS patients. Interaction between cytokines and specific IgE antibodies.

Basophil leukocytes obtained from AIDS patients, allergic patients and healthy controls were stimulated in vitro with interleukin 4, lymphotoxin, tumour necrosis factor alpha and interferon gamma to examine the histamine releasing effect. The cytokines caused histamine release from the basophils of approximately half the AIDS patients and from 8-17% of the allergic patients. No response was obtained in the control group. Removal of cell surface immunoglobulins abolished the response to cytokines, indicating an Ig-dependent mechanism. Passive sensitization with cell-derived Ig, with Ig deprived of IgE, or with IgG, indicated that cell-bound IgE was responsible for the cytokine-induced histamine release in AIDS patients. This response may be mediated by cytokine-selective IgE antibodies.

Acquired Immunodeficiency Syndrome

Virus, bacteria and lipopolysaccharide increase basophil cell response to histamine releasing stimulators and calcium. Examination of allergic and normal individuals.

Histamine release from human basophil leukocytes from allergic patients or controls was induced by specific antigens, anti-IgE or calcium ionophore A23187. Influenza A virus, S. aureus and lipopolysaccharide from S. typhimurium increased the maximum release of histamine and caused a shift to the left of the dose-response curves showing increased cell sensitivity and lowering of the threshold to these stimuli. The mechanism of action was elucidated by examining the mediator release as a function of increasing extracellular concentration of calcium. In these experiments the dose-response curves were changed by the microorganisms and lipopolysaccharide as before. This indicates that the microorganisms and lipopolysaccharide change the basophil cell response to IgE-dependent and non-immunological stimuli by causing a change in the subcellular handling of calcium.

Adult

Carbohydrates inhibit the potentiating effect of bacteria, endotoxin and virus on basophil histamine release.

Histamine release caused by calcium ionophore A23187 and anti-IgE was examined in leukocyte suspensions from 8 healthy individuals. Staphylococcus aureus, lipopolysaccharide (LPS) from Salmonella typhimurium and influenza A virus were found to enhance the histamine release but did not release histamine per se. The potentiation of mediator release depends on a non-transient signal since the potentiating effect was also obtained by preincubation of the cells with LPS followed by wash-out and stimulation of the cells with anti-IgE. The potentiation was abolished or reduced by galactose, N-acetyl-glucosamine, alpha-methyl-D-glucoside, alpha-methyl-D-mannoside, N-acetylneuraminic acid and lactose, but not by glucose. These findings indicate that the enhancement of mediator release by bacteria, endotoxin, and virus depends on a sugar-mediated reaction.

Basophils

Haemophilus influenzae potentiates basophil histamine release possibly by its endotoxins.

Haemophilus influenzae and its extracellular products (EP) did not release histamine in leukocyte suspensions from normal individuals. However, the EP were found to enhance basophil histamine release triggered by anti-IgE and by the calcium ionophore A23187. Experiments with EP indicate that it is the content of endotoxins which is responsible for the potentiating effect. Removal of endotoxin from the EP thus completely abolished the potentiating effect, whereas inactivation of its protease and proteins by heat-treatment or by proteinase K did not change the potentiation. A reinforcement of mediator release by the extracellular products of H. influenzae might play a pathophysiological role in chronic obstructive pulmonary disease.

Basophils

Virus enhances IgE- and non-IgE-dependent histamine release induced by bacteria and other stimulators.

Histamine release from human basophil leukocytes was triggered by Staph. aureus, Salmonella enteritidis, non-haemolytic streptococci, or E. coli. Influenza A virus was found to enhance the mediator release and the effect was caused by synergism, since the virus did not induce release of histamine per se. This potentiating effect of the virus was seen both when the bacteria-induced histamine release was IgE-dependent (i.e. patient sensitized to the bacterium) and when the bacterium caused mediator release by a non-immunological mechanism independent of IgE (putative sugar-lectin mediated). Histamine release induced by anti-IgE and calcium ionophore or agarose-beads was also enhanced in the presence of the virus. These findings indicate that influenza A virus potentiates both IgE- and non-IgE-mediated histamine release induced by bacteria and other stimulators.

Bacterial Infections

Cytokine-induced release of histamine from basophil leukocytes from AIDS patients.

Cytokine-induced histamine release from basophil leukocytes was examined in cell suspension from AIDS patients and compared with healthy controls. Cells from approximately half of the AIDS patients, in contrast to none from the control group, showed histamine release after stimulation with interleukin-4 (IL-4), tumor necrosis factor alpha (TNF alpha), lymphotoxin (LT) and interferon gamma (IFN gamma). These cytokines seem to induce histamine release from cells from AIDS patients by interaction with the cell surface immunoglobulins, since removal of the immunoglobulins prior to the exposure of the cytokines completely abolished the response to the cytokines. IL-1 alpha, IL-1 beta, IL-3, colony stimulating factor (CSF) and granulocyte-macrophage-CSF (GM-CSF) caused significant histamine release from cells from a similar number of AIDS patients and controls.

Acquired Immunodeficiency Syndrome

Endotoxin from Haemophilus influenzae enhances IgE-mediated and non-immunological histamine release.

Haemophilus influenza and its extracellular products (EP) did not release histamine from basophil leukocytes in cell suspensions from normal individuals, patients with chronic bronchitis or patients allergic to either house dust mite, grass pollen, cat dander or to their own bacteria. However, the EP was found to enhance their basophil histamine release. IgE-mediated histamine release was examined by stimulation of the cells with anti-IgE or the specific allergens, and non-immunological histamine release by stimulating the cells with the calcium ionophore A23187 or Staphylococcus aureus. In all the experiments EP caused a significant increase in the histamine release. When H. influenzae endotoxins were removed from the EP, the potentiating effect of EP was completely abolished, whereas heating (80 degrees C, 30 min) or treatment of EP with proteinase did not influence the potentiating effect. These results indicate that H. influenzae endotoxin potentiates histamine release caused by IgE-mediated reactions or by non-immunological mechanisms.

Adult

Bacteria and endotoxin enhance basophil histamine release and potentiation is abolished by carbohydrates.

Histamine release caused by anti-IgE, specific antigens and calcium ionophore A23187 was examined in leukocyte suspensions from healthy individuals and patients allergic to house dust mite and birch pollen. Staphylococcus aureus and LPS from Salmonella typhimurium were found to cause a synergistic enhancement of the release. The potentiation of mediator release by the bacteria and the endotoxin depends on a binding to the basophilocyte, followed by a non-transient event, since the potentiating effect persists after preincubation of the cells with the LPS followed by washout and leaving the cells for 30 min at 37 degrees C before stimulation with anti-IgE. The potentiation was abolished or reduced by galactose (10(-7) and 10(-6) M) and N-acetylglucosamine (10(-6) and 10(-5) M), acting by a binding to the basophil cell membrane, demonstrated by the persistence of effect after preincubation and washout of unbound sugar.

Adult

Influenza A virus potentiates bacteria-induced histamine release. Examination of normal individuals and patients allergic to bacteria.

Influenza A virus was found to enhance basophil histamine release induced by Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus sanguis, but did not per se release histamine. This potentiating effect of the virus was seen both when the bacteria-induced mediator release was IgE-dependent (i.e. patient allergic to bacterium) and when the bacterium caused histamine release by a non-immunological mechanism independent of IgE (putative sugar-lectin mediated). Also histamine release induced by other immunological and non-immunological stimuli, such as anti-IgE, calcium ionophore or agarose beads was enhanced in the presence of the virus. The potentiating effect of the virus on bacteria-induced mediator release might be of importance for the conversion from latent to manifest asthma in upper respiratory tract infections.

Adult

Influenza A virus enhances basophil histamine release and the enhancement is abolished by carbohydrates.

Basophil histamine release was studied in leukocyte suspensions from normal individuals and from patients allergic to house dust mite or birch pollen. Mediator release caused by IgE-mediated reactions was examined by stimulating the cells with anti-IgE or specific antigens, and the calcium ionophore A23187 was used for a non-immunological histamine release. In all experiments influenza A virus caused a synergic enhancement of the mediator release and the potentiation was abolished by galactose (10(-7) to 10(-6) M) and by 10(-6) to 10(-5) M of N-acetylglucosamine, alpha-methyl-D-glucoside, alpha-methyl-D-mannoside, N-acetylneuraminic acid and lactose, but not by glucose. Wash-out experiments show that the sugars prevent the aggravation of mediator release by a binding of sugar to the basophil cell membrane, thereby causing a blockade of binding sites responsible for the potentiating effect of virus.

Adult