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Biomedical subjects

J Hed

Publications and source records attributed to J Hed.

At least 91 records · Page 5Linked to original sources
PubMed1984

Myeloperoxidase modulates the phagocytic activity of polymorphonuclear neutrophil leukocytes. Studies with cells from a myeloperoxidase-deficient patient.

Patients lacking the primary granulae enzyme, myeloperoxidase (MPO), do not usually show any increased susceptibility to infection or altered inflammatory response, in contrast to several other biochemical defects in polymorphonuclear neutrophils. We have now evaluated the role of MPO on phagocyte function in a patient with complete MPO deficiency suffering from generalized pustular psoriasis. We found that the MPO-deficient neutrophils showed enhanced phagocytosis (greater than 200% of normal) of IgG- and C3b-opsonized yeast particles and prolonged N-formylmethionyl-leucyl-phenylaline-mediated stimulation of superoxide production. When purified human MPO was added to normal neutrophils during cell adhesion, their Fc- and C3b-mediated phagocytosis was reduced without affecting cell viability. 1 microgram/ml of MPO reduced the Fc and C3b phagocytosis to 47 and 65%, respectively, whereas 10 micrograms/ml reduced the activity to 20 and 54%. Both attachment and ingestion were reduced to a similar extent, indicating that MPO affected the receptor function per se. When MPO was added to the hyperactive MPO-deficient cells, phagocytosis was reduced more rapidly. Catalase, azide, and methionine eliminated the inhibitory effect, and catalase and methionine, in fact, enhanced the phagocytic activity of adherent neutrophils. These data indicate that, apart from being a potent antimicrobial system, the oxidizing activity of the MPO-H2O2-halide system may modulate the inflammatory response by impairing certain receptor-mediated recognition mechanisms of phagocytic cells, which otherwise could elicit inflammatory reactions and tissue injury.

Complement C3b↗
PubMed1984

Changes in circulating immune complexes in tumour patient serum after in vitro or ex vivo affinity chromatography of blood plasma or whole blood over immunoglobulin-binding staphylococcal protein A-Sepharose.

Circulating immune complexes (CIC) were determined in tumour patient sera using three methods. One is based on PEG-precipitation, one on C1q-reactivity, and one on protein A-reactivity. About 25-30% of the sera were positive in at least one of the tests. Incubation of serum with protein A-Sepharose in vitro removed PEG-precipitable CIC from most sera, whereas C1q-reactive CICs had a much lower affinity to protein A. The protein A-reactive complexes showed considerable variation in their binding to protein A-Sepharose, and in some sera the amount of these CICs was actually increased. Similar changes in protein A-reactive CIC were also found during ex vivo treatment of tumour patients with immune adsorption. It is proposed that the binding of immune complexes to protein A can result in remodelling of protein A itself. Results from ultracentrifugation and fractionated PEG-precipitation support this hypothesis.

Antigen-Antibody Complex↗
PubMed1983

A quantitative microassay for leukocyte chemotaxis, using a microscopic slide system with complement-activating yeast particles as gradient source.

A simple quantitative microassay was developed for studying polymorphonuclear leukocyte (PMNL) chemotaxis under conditions where the number of available cells is a limiting factor, e.g., pustules, neutropenia, small children and cerebrospinal fluid. PMNL suspensions are placed on glass slides to which fluorescein-labeled yeast particles have been fixed. After adherence, normal human serum is added to the slides. Owing to complement activation, a chemotactic gradient which attracts the adherent PMNL is formed around the yeast particles. The number of PMNL-associated yeast particles in the presence of normal serum is scored, and compared with cells migrating in the presence of inactivated serum or in the absence of serum. A locomotory index is calculated as the number of yeast particles associated with PMNL divided by the total number of yeast particles.

Blood Physiological Phenomena↗
PubMed1983

Differentiation between attached and ingested immune complexes by a fluorescence quenching cytofluorometric assay.

Immune complexes attached to and ingested by human polymorphonuclear (PMN) cells were quantified by cytofluorometry using a fluorescence quenching assay which permits differentiation between attachment and ingestion. The fluorescence intensity decreased after ingestion as a result of the low pH in the phagolysosomes. When extracellular pH was lowered a slight decrease in phagolysosomal pH was detected in macrophages but not in PMN. When measuring total fluorescence, interaction at pH 5.8 for PMN and at pH 4.4 for macrophages is recommended, since the intensity of extra- and intracellular fluorescence are equal under these conditions. Thirty different dyes were tested for dye exclusion and fluorescence quenching of FITC-conjugated yeast particles, and FITC-conjugated IgG. Because of the lysosomotropic effect of basic dyes, acid and direct dyes are preferable as quenching agents. We could not find physical or chemical properties of the dyes that correlated with their quenching effect. Heat aggregated IgG was used as an immune complex analogue in the development of the assay. Trypan blue (0.2 mg/ml) at pH 4.4 was found to be the best quenching agent of extracellular fluorescence when using ingested aggregated IgG. The technique offers a simple method of quantifying ingested protein aggregates and of studying heterogeneity in phagocyte populations.

Animals↗
PubMed1983

The stabilization of the C3b molecule in immune deposits by formalin.

Formalin-fixed tissue may be used as substrate for immunohistochemistry after enzymatic treatment with proteases. However, whether the antigenicity of C3b is restored is controversial owing to the protease sensitivity of the native molecule. The antigenicity and protease sensitivity of formalin-fixed and non-fixed C3b were tested by using C3b-opsonized yeast particles and the immunofluorescence technique. The results indicate that formalin, probably due to cross-linking, stabilizes C3b molecules and renders them less susceptible to protease treatment. Failures to detect C3b in immune deposits in fixed tissues may be due to factors other than protease treatment.

Animals↗
PubMed1983

A simple fluorescence technique to stain the plasma membrane of human neutrophils.

Three different fluorochromes were tested for their ability to label the plasma membrane proteins of neutrophils without labelling intracellular structures. A fluorescence quenching technique was used to differentiate between extra- and intracellularly localized fluorescence. Fluorescamin and fluoresceinisothiocyanate were shown to stain intracellular structures as well as the plasma membranes of the cells. Another fluorochrome, Evans Blue, is proposed since this dye was shown, by using the fluorescence quenching technique, to selectively stain the plasma membrane of viable neutrophils.

Cell Membrane↗
PubMed1983

Prizidilol, a combined vasodilatory and beta-adrenoceptor blocking drug, in primary hypertension. A long-term efficacy, tolerance and pharmacokinetic study.

After an initial placebo period of four weeks 24 patients with primary hypertension were treated with prizidilol, a hydrazinopyridazine derivative with combined vasodilator and non-selective beta-adrenoceptor blocking actions, for a dose titration period of 14 weeks. Prizidilol 200 to 800 mg was given once daily to achieve a target supine diastolic blood pressure (BP) less than 90 mmHg. Supine and standing BP recorded 24-27 h after drug intake decreased from 172 +/- 17/106 +/- 6 mmHg (mean +/- SD) and 167 +/- 18/111 +/- 8 mmHg, respectively, after placebo to 159 +/- 16/99 +/- 8 and 154 +/- 18/101 +/- 9 mmHg after active treatment for six weeks (mean dose 447 mg), and to 154 +/- 16/97 +/- 7 and 148 +/- 14/97 +/- 7 mmHg after treatment for 14 weeks (mean dose 687 mg/day). A slight reduction in HR was seen after treatment for six weeks and in plasma renin activity and urinary methoxycatecholamine excretion after treatment for 14 weeks. A sustained decrease in BP was observed for 10 h after prizidilol 800 mg (n = 9), with a maximum antihypertensive effect (mean reduction in supine BP 33/18 mmHg) 2.5 h after dosing, which coincided with the mean peak plasma concentration. The plasma elimination half-life of the drug was 3.9 h (range 2.0-8.9 h). Changing to a twice daily regimen in 17 patients (mean daily dose 748 mg at six months) did not produce any further reduction in the BP (recorded 12-15 h after dosing) as compared to the once daily regimen at 14 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylation↗
PubMed1982

Physicochemical and functional changes in human leukemic cell line HL-60.

The recently established human promyelocytic cell line HL-60 was induced to differentiate in the present of DMSO. During this process, physicochemical, and functional changes were detected simultaneously. After exposure to DMSO for more than 1 day, the cell volume decreased and the tendency for hydrophobic interaction increased. Using a hydrophobic two-phase system in counter current distribution fashion, it was then possible to separate more mature metamyelocytes and segmented granulocytes from immature myeloblasts and promyelocytes. Increased functional maturity was reflected by increased chemiluminescence (CL) response and phagocytic activity. Using yeast particles opsonized with IgG as stimulating agent, the CL response increased already after 1 day in DMSO, in parallel with increased phagocytosis of these particles. In contrast, C3b-opsonized yeast and phorbol 12-myristate 13-acetate (PMA) did not enhance the CL response conspicuosly until days 3-4. These data suggest that Fc receptor function linked to phagocytosis and the activation of oxidative metabolism develop earlier than that of C3b and PMA. The dissociation between Fc- and PMA-dependent stimulation of the oxidative metabolism may reflect different mechanisms of activation.

Cell Differentiation↗
PubMed1982

Physicochemical surface changes on phagocytic cells during differentiation in relation to chemotaxis and phagocytosis.

During cell differentiation induced by DMSO, the HL-60 cells exhibit certain surface alterations such as increased hydrophobic interaction. Similar changes have been observed in activated alveolar macrophages, and granulocytes exposed to chemoattractant in vivo and in vitro. Whether these surface changes are directly linked to the enhanced chemotactic, oxidative and phagocytic responsiveness is unclear, although increased liability to hydrophobic interaction promotes phagocytic recognition in several systems. From the present data it is evident that oxidative and phagocytic responsiveness are acquired at different stages of differentiation. Detecting physicochemical differences in the surface properties of the HL-60 cells during differentiation may furthermore provide a useful tool for studying subpopulations of cells during differentiation and activation.

Cell Differentiation↗
PubMed1982

Combined immunomorphological examination of epon-embedded human kidney biopsies: a comparative study between cryostat, paraffin and consecutive epon-embedded sections for detection and localization of immune deposits.

Immunomorphologic analysis of glomerulopathies in human kidney biopsies can be achieved in sections embedded in Epon. Formalin fixation followed by protease treatment of the tissue before dehydration and embedding are the essential steps in the incubation method which permit the detection of both immunoglobulins and complement (C3). The sections can be used for comparative light, phase contrast, and electron microscopic examination. This method is superior to paraffin and methacrylate embedding techniques for detailed immunomorphology.

Basement Membrane↗
PubMed1982

Interaction between human polymorphonuclear leukocytes and two different strains of type 1 fimbriae-bearing Escherichia coli.

Two type 1 fimbriae-bearing strains of Escherichia coli, ABU2 (ON:K14) and PN7 (O1:K1), with different underlying physicochemical surface properties were compared for their capacity to interact with human polymorphonuclear leukocytes. Both strains attached strongly to neutrophils in a mannose-sensitive manner. One of the strains, ABU2, with a surface exposing weak negative charge and liability to hydrophobic interaction, was efficiently ingested (65%) and caused a release of reactive oxidative metabolites (chemiluminescence) and lysosomal enzymes. The other strains, PN7, exposing a hydrophilic, negatively charged K antigen and hydrophilic uncharged smooth lipopolysaccharide, resisted phagocytosis (only 25% were ingested) but nevertheless caused a release of reactive oxidative metabolites and lysosomal enzymes to a greater extent than did phagocytosed strain ABU2. These results show that attachment mediated by type 1 fimbriae does not ultimately lead to ingestion. Whether the attached bacteria are being ingested or not depends on their underlying physicochemical surface properties. Furthermore, if the bacteria remain extracellularly attached, they may potentiate the inflammatory process.

Adhesiveness↗
PubMed1982

In vitro effect of hydrocortisone on the attachment and ingestion phases of immunoglobulin G- and complement component 3b-mediated phagocytosis by human neutrophils.

The fluorescence quenching method (FQ method) was used to investigate the effect of hydrocortisone on the attachment and ingestion phases of immunoglobulin G (IgG)- and complement component 3b (C3b)-mediated phagocytosis by human neutrophils (PMNs). The results were compared with metabolic activity (O2- release) of the phagocytes. When the PMNs were treated with 5 X 10(-5) M hydrocortisone or more, both IgG-mediated and C3b-mediated interactions decreased. The number of intracellular particles decreased as the total number of PMN-associated particles decreased, indicating an effect mainly on particle attachment. This was substantiated by the fact that pretreatment of the PMN with cytochalasin B resulted in a hydrocortisone dose-related decrease of interacting particles. The FQ method made it possible to quantify the stimulus-phagocyte interaction in relation to the metabolic response. Superoxide anion release decreased at the highest concentration of hydrocortisone used (5 X 10(-3) M), which merely reflected the decreased number of interacting particles. No reduction in metabolic activation was obtained when the superoxide anion release was correlated with the number of interacting yeast-IgG particles. The results indicate that hydrocortisone primarily affects the binding capacity of Fc and C3b receptors, resulting in decreased metabolic activation. The effector functions, e.g., ingestion and metabolic activation, were not affected by hydrocortisone in this study.

Complement C3b↗
PubMed1982

Complement-mediated inhibition of non-specific aggregation of highly-dinitrophenyl-conjugated human serum albumin.

125I-labelled dinitrophenylated human serum albumin (DNP35HSA) was shown to form large aggregates after incubation either in normal human serum (NHS) containing ethylene diamine tetraacetate (EDTA), or in heat treated NHS, whereas much smaller aggregates were formed after incubation in NHS or NHS containing ethylene glycol tetraacetate (EGTA) and Mg2+. It is proposed that serum complement inhibits the formation of DNP35HSA aggregates after activation of the alternative pathway in the absence of specific antibodies. The phenomenon is probably explained by increased electrostatic repulsion.

Antigen-Antibody Complex↗
PubMed1982

Autoantibody activities of human IgM M-components.

By means of indirect immunofluorescence microscopy we have shown that 11 out of 18 (61%) IgM M-components from patient sera had affinity for various tissue structures. The great variation in affinity patterns, and the high titres support the antigen-antibody mode of interaction. The high incidence of activity against smooth muscle (4/18) shown in this study, and against IgG, and red blood cell antigens shown by others indicates that the onset of IgM M-component production is initiated in situations where a polyclonal IgM-antibody response is the rule. Beside specific antibody activities, the M-components tested showed affinity for gastric epithelium and hepatocytes. The titres correlated roughly to the serum concentrations of IgM, and the patterns corresponded to the localization of secretory component as shown by others indicating a non-antigen--antibody reaction between the IgM M-components and secretory component.

Animals↗
PubMed1981

Detection of immune deposits in glomeruli: the masking effect on antigenicity of formalin in the presence of proteins.

Formalin is known to mask the antigenicity of immune deposits in glomeruli but not of surface immunoglobulins of isolated lymphocytes. We have shown in mice with experimental passive anti-GBM glomerulonephritis that formalin masks the antigenicity of GBM-bound immunoglobulins only if the tissue is fixed before sectioning. The presence of a high concentration of normal bovine serum during fixation of cryostat sections masks the antigenicity of immune deposits, whereas formalin alone has no obvious effect. The same results were obtained with human immunoglobulins (IgG, IgM and IgA) bound to tissue sections. Protease treatment with pepsin and trypsin restored the ability of the immunoglobulins to be stained. The masking effect seems to be due to extensive cross-linking of environmental proteins which prevents fluorescent conjugates reaching their antigens. Methods for detecting immunoglobulins in tissues must, therefore, take into consideration the influence of fixatives not only on epitopes but also on the environment in which the antigenic determinants are localised.

Animals↗
PubMed1981

Gluten-free diet for dermatitis herpetiformis: the long-term effect on cutaneous, immunological and jejunal manifestations.

In 32 patients with dermatitis herpetiformis (DH) we studied the effect of gluten-free (22 patients) and gluten-reduced (10 patients) diet for periods ranging between 15 and 43 months. Variables such as cutaneous manifestations, dependence on dapsone, IgA deposits in the skin, small-bowel function, and jejunal mucosal morphology were studied. 59% of the patients on gluten-free diet could stop dapsone medication and remain symptom-free, compared with 10% on gluten-reduced diet. The time needed to achieve this therapeutic response varied from 5 to 31 months. IgA decreased in the skin to a degree which roughly paralleled the morphological normalization of the jejunal mucosa. In no patient, however, did the IgA completely disappear. It is suggested that IgA is not the main factor inducing DH symptoms, but rather a secondary phenomenon. Repeated jejunal biopsies revealed normalization of the mucosal histology in 52% of the patients on gluten-free diet, compared with none in the gluten-reduced diet group.

Adolescent↗