Search PubMed⌕ Search

Biomedical subjects

A B Kay

Publications and source records attributed to A B Kay.

At least 235 records · Page 13Linked to original sources
PubMed1990

IL-5 enhances the in vitro adhesion of human eosinophils, but not neutrophils, in a leucocyte integrin (CD11/18)-dependent manner.

In an attempt to explain the preferential accumulation of eosinophils at sites of allergic tissue reactions, we have studied the effects of interleukin-5 (IL-5) on the adherence of human eosinophils and neutrophils to plasma-coated glass (PCG) or human microvascular endothelial cells (HMVEC). IL-5 was compared with IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF) and platelet-activating factor (PAF), since all these agents have biological properties associated with eosinophil activation and/or survival in vitro. IL-5, IL-3 and GM-CSF induced a time-dependent increase in adherence of normal density eosinophils to PCG optimal at 60 min, whereas the effect of PAF was greater at 15 min. Similar results were obtained with neutrophils, with the exception that IL-5 had minimal and non-significant effects on this cell type. Unstimulated eosinophils and neutrophils also adhered to PCG or HMVEC, but in low numbers. Preincubation of eosinophils with IL-5, GM-CSF or PAF resulted in dose-dependent increases in the numbers of adherent cells to PCG. IL-3 had a smaller but significant effect on enhanced eosinophil adhesion to PCG, while IL-2 and lyso-PAF were ineffective. Neutrophils gave similar levels of baseline and stimulated adhesion to PCG as eosinophils, IL-5 again had no significant stimulatory effect. IL-5 also increased eosinophil, but not neutrophil, adherence to HMVEC in a concentration-dependent manner. Preincubation with the protein synthesis inhibitor cycloheximide had no effect on IL-5-, GM-CSF- or PAF-stimulated eosinophil adhesion. The contribution of the CD11/18 leucocyte integrins to IL-5- and PAF-induced eosinophil hyperadherence was investigated by inhibition experiments utilizing monoclonal antibodies (mAb). Enhanced adhesion to PCG (by PAF) or HMVEC (by IL-5) was inhibited by (ranked in order of potency) anti-CR3 alpha = common beta-chain greater than LFA-1 alpha. Anti-p150,95 alpha had no measurable effect. Baseline adhesion by unstimulated eosinophils was not significantly influenced by prior incubation with these mAb. Using flow cytometry, IL-5 and IL-3 were found to up-regulate cosinophil but not neutrophil CR3 expression. These findings demonstrate that IL-5 enhances cosinophil, but not neutrophil, adherence reactions, by a mechanism dependent, at least in part, on the CD11/18 family of adhesion glycoproteins.

Cell Adhesion↗
PubMed1990

Release of leukotriene C4 (LTC4) from human eosinophils following adherence to IgE- and IgG-coated schistosomula of Schistosoma mansoni.

The release of leukotriene C4 (LTC4) from human low-density eosinophils following adherence to live or formalin-fixed schistosomula of Schistosoma mansoni coated with parasite-specific IgE or IgG obtained from pooled human anti-S. mansoni serum has been studied. IgE-rich fractions were obtained after fractionation of pooled immune sera on fast-protein liquid chromatography (FPLC; polyanion SI-17 column) and were identified by parasite-specific RAST. Contaminating IgG was removed by adsorption on a Staphylococcus aureus-protein A affinity column. IgG-rich FPLC fractions were identified by a specific ELISA assay. IgG-dependent activities were confirmed by protein A adsorption. Low-density eosinophils adhered to live and formalin-fixed schistosomula coated with specific antisera and released 11.7 +/- 2.7 and 16.5 +/- 3.5 pmoles of LTC4/10(6) cells, respectively. LTC4 release induced by A23187 (5 x 10(-6) M) from the same cells was 80 +/- 24 pmoles/10(6) cells and 9.9 +/- 1 pmoles/10(6) cells in the presence of Sepharose particles (CNBr-activated 4B beads) covalently coated with normal human IgG. Fixed schistosomula coated with FPLC-purified IgE and IgG gave 7.6 +/- 0.4 and 6.0 +/- 0.1 pmoles of LTC4 per 10(6) low-density eosinophils, respectively. The same IgE- and IgG-rich fractions induced eosinophil-mediated cytotoxicity of live schistosomula in vitro. Removal of IgE by an anti-IgE affinity column abolished both the IgE-dependent release of LTC4 and the in vitro killing of larvae. Conversely, IgG-dependent activities were abolished by protein A, but not anti-IgE, adsorption. Normal density eosinophils generated undetectable amounts of LTC4 when incubated with IgE-coated schistosomula, whereas with IgG-coated larvae 4.6 pmoles/10(6) cells were obtained. Following preincubation with platelet-activating factor (PAF) (10(-7) M) and leukotriene B4 (LTB4) (10(-7) M), normal density eosinophils released LTC4 when in contact with larvae coated with antigen-specific IgE. Lyso-PAF had no effect in any of the systems tested. The synthetic chemotactic tripeptide formyl-methionyl-leucyl-phenylalanine (FMLP) had no influence on IgE-dependent release of LTC4 from eosinophils. In contrast, FMLP (10(-7) M) enhanced the IgG-dependent LTC4 release, with PAF and LTB4 also showing a small enhancing effect. None of these agents substantially altered the release potential of low-density eosinophils in either IgE- or IgG-dependent events. Thus the results presented here indicate that in an IgE-dependent system, human low-density eosinophils can be induced to adhere to and kill IgE-coated helminthic targets and release biologically relevant amounts of LTC4.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

The effect of platelet-activating factor on IgE binding to, and IgE-dependent biological properties of, human eosinophils.

This study investigated the effect of platelet-activating factor (PAF), leukotriene B4 (LTB4) histamine and formyl-methionyl-leucyl-phenylalanine (FMLP) on immunoglobulin E (IgE) binding and IgE-dependent cytotoxicity of human normal density eosinophils. The binding of a native myeloma IgE to normal human eosinophils was measured by flow cytometry using a fluorescein-conjugated polyclonal anti-IgE antibody. Preincubation with PAF (optimal at 10(-7)M), but not lyso-PAF or FMLP, gave dose-dependent increases in IgE binding. PAF and LTB4 gave significant increases in IgE binding after 5 min preincubation (P less than 0.05); the effect was further enhanced at 30 min (P less than 0.01). This was further confirmed using the rosette assay where PAF and LTB4, but not lyso-PAF or FMLP, gave dose- and time-dependent increases in IgE eosinophil rosettes. Eosinophil cytotoxicity for schistosomula of Schistosoma mansoni, incubated with immune serum, was also significantly enhanced (P less than 0.01) by PAF in a dose-dependent fashion (optimal at 10(-8) M). Schistosomula coated with FPLC-purified IgE fractions were susceptible to killing by normal density eosinophils, and this was enhanced with PAF (10(-8)M), LTB4 (10(-7)M) and histamine (10(-5)M) but not with FMLP (10(-7)M) or lyso-PAF. IgE-dependent cytotoxicity was confirmed by the removal of contaminating IgG from IgE-rich fractions, and by the abolishment of IgE-dependent cytotoxicity after IgE adsorption. These results suggest that PAF (and to a lesser extent LTB4 and histamine) increase IgE binding, IgE-dependent adherence and cytotoxicity of normal human eosinophils. Although IgE receptors have not been identified, the data support current concepts that certain biological properties of eosinophils may be IgE associated.

Cells, Cultured↗
PubMed1989

Leukotriene release enhancing factor. Purification, specific allergen induction, and further biologic properties.

Human PBMC cultured with PHA produced a factor which enhanced neutrophil LTB4 production. After progressive purification by gel filtration and chromatofocusing, leukotriene release enhancing factor (LREF) gave a single band on SDS-PAGE corresponding to a Mr of 60 kDa and a isoelectric point of 5.0 to 5.2. Human T lymphocytes were identified as a source of LREF because a long term human CD4+ T cell line, specific for house dust mite (Dermatophagoides farinae) generated leukotriene release enhancing activity (LREA) when stimulated with the inducing Ag together with irradiated accessory cells. Cultures of accessory cell and Ag alone did not induce neutrophil activation. Similarly, control cultures using an irrelevant allergen (grass pollen) failed to produce this activity. Stimulation of PBMC with anti-CD3 mAb also generated LREA. LREA had other neutrophil-associated biologic activities. These included the enhancement of neutrophil adherence to nylon wool, increased cytotoxicity of opsonised schistosomula of Schistosoma mansoni and upregulation of C receptors (CR1 and CR3). LREA had minimal neutrophil chemotactic activity. Therefore, LREF has potential as a mediator of inflammation and provides a link between lipid mediators, neutrophils, and cell-mediated immunity in the context of allergic diseases.

Adjuvants, Immunologic↗
PubMed1989

Mast cells in human lungs.

Mast cells were stained deeply in human lung tissue with acidic toluidine blue to obtain maximum numbers possible in paraffin sections. One hundred high-power fields were counted per section, and mean and median values summarized as mast cells per mm2. Immersion-fixed samples of fresh lung tissue (not bronchi) were taken as controls from seven patients after surgery, and showed mean values of 44.7 mast cells per mm2 after formalin fixation, and 51.9 per mm2 after Carnoy's fixative. Mast cell heterogeneity may explain these differences, but so could random variation between counts. In two patients with extrinsic allergic alveolitis (hypersensitivity pneumonitis), fresh lung tissue from open lung biopsies showed raised values of 90.8 and 101.9 mast cells per mm2, matching the high mast cell counts reported in bronchopulmonary lavage fluid in the condition. Control post-mortem lung tissue from two patients dying of non-pulmonary diseases showed mean values of 26.1 and 50.6 mast cells per mm2. Post-mortem lung tissue from three patients dying of asthma showed very low mean values of 4.7, 5.7, and 5.9 mast cells per mm2. Low mast cell counts due to severe degranulation have been reported before in the bronchi in asthma deaths, but not, to our knowledge, in the lung parenchyma. This finding implies a wider area of mediator release, and helps to explain the severity of the acute attack, and the fatal outcome.

Alveolitis, Extrinsic Allergic↗
PubMed1989

Leukotrienes, LTC4 and LTB4, in bronchoalveolar lavage in bronchial asthma and other respiratory diseases.

Leukotrienes (LTs) C4 and B4 are potent proinflammatory mediators with a wide variety of biologic activities, including smooth muscle contraction, mucus hypersecretion, and leukocyte activation, which may be of particular relevance to the pathology of asthma and other respiratory diseases. We measured the concentrations of LTC4 and LTB4 in bronchoalveolar lavage fluid from 16 atopic subjects with asthma (eight symptomatic and eight asymptomatic) and from 14 control subjects without asthma (six with hay fever and eight nonatopic). The amounts detected in symptomatic subjects with asthma were significantly higher than in control subjects (LTB4, 0.58 +/- 0.06 versus 0.36 +/- 0.05 pmol/ml, p less than 0.05; LTC4, 0.36 +/- 0.1 versus 0.12 +/- 0.02 pmol/ml, p less than 0.01). LTC4 and LTB4 were also measured in 17 patients: nine with interstitial lung disease of varying etiology (cryptogenic fibrosing alveolitis [CFA] or idiopathic pulmonary fibrosis), three with sarcoidosis, one with extrinsic allergic alveolitis, one with sulphonamide-induced pneumonia, and one patient with eosinophilic granuloma. The concentrations of LTB4 (but not LTC4) were significantly greater in patients with CFA compared with normal control subjects (0.69 +/- 0.3 versus 0.36 +/- 0.05 pmol/ml, p less than 0.01). There was a significant correlation (p less than 0.05) between the percentage of neutrophils and the concentration of LTB4 in the bronchoalveolar lavage fluid) of the group with interstitial lung disease as a whole. This study provides evidence for a role for LTs in the airways of subjects with day-to-day asthma and suggests that LTB4 may also be involved in the recruitment of granulocytes into the lung in patients with CFA.

Adult↗
PubMed1989

Blood eosinophils and eosinophil-derived proteins in allergic asthma.

The concentrations of the eosinophil (EOS)-derived proteins, major basic protein (MBP), EOS-derived neurotoxin (EDN), EOS peroxidase (EPO), and EOS cationic protein (ECP), and EOS counts were measured in the peripheral blood of 12 atopic subjects with asthma and 23 normal control subjects. The same measurements were performed in seven subjects with asthma with previously documented dual (early plus late) asthmatic responses after inhalation challenges with methacholine and allergen. EOSs (p less than 0.001), MBP (p less than 0.01), EDN (p less than 0.01), and ECP (p greater than 0.03) were elevated in the subjects with asthma compared with control subjects, whereas EPO (p less than 0.01) concentrations were reduced. There were no significant differences between baseline measurements of FEV1, EOSs, MBP, EDN, EPO, or ECP on the methacholine- and allergen-challenge days. When the changes in these variables after allergen challenge were compared with the corresponding changes after methacholine challenge, there were no significant differences at 0 to 60 minutes or at 3 hours, whereas EDN (p less than 0.025), EPO (p less than 0.05), and ECP (p less than 0.025) were relatively increased at 6 to 12 hours and accompanied the late falls in FEV1 (p less than 0.001). EOSs (p less than 0.025) were elevated at 24 hours when there was a small relative increase in MBP (p less than 0.05). EOSs appear to be "activated" in subjects with allergic asthma, and further activation may occur during late asthmatic responses.

Adult↗
PubMed1989

Inhibition of platelet-activating factor (PAF)-induced chemotaxis and PAF binding to human eosinophils and neutrophils by the specific ginkgolide-derived PAF antagonist, BN 52021.

We have investigated the effects of BN 52021 (a specific PAF antagonist derived from Ginkgo biloba) on PAF-induced human eosinophil and neutrophil chemotaxis. In response to an optimal concentration of PAF (10(-6) mol/L), the drug was significantly more potent (p less than 0.001) in inhibiting eosinophil as compared to neutrophil locomotion. These inhibitory effects were observed in a dose-dependent manner with a concentration of drug required to produce 50% inhibition of 7.0 (+/- 2.2) X 10(-6) mol/L and 2.3 (+/- 0.2) X 10(-5) mol/L for eosinophils and neutrophils, respectively. Sodium cromoglycate, nedocromil sodium, salbutamol, and dexamethasone (preincubated with cells up to 6 hours) had no effect over a wide dose range (10(-3) to 10(-9) mol/L). BN 52021 was significantly more effective in inhibiting chemotaxis when the cells were preincubated with the compound for up to 1 hour before commencement of the locomotion assay, whereas washing the cells completely abolished this effect. Inhibition by BN 52021 was specific for PAF in that it had no effect on chemotaxis induced by either leukotriene B4, N-formyl-methionyl-leucyl-phenylalanine, or a purified human mononuclear cell-derived neutrophil chemotactic factor. BN 52021 also inhibited the specific binding of [3H]-PAF (10(-8) mol/L) to eosinophils and neutrophils in a concentration-dependent fashion with a concentration of drug required to produce 50% inhibition of 1.5 (+/- 0.3) X 10(-6) mol/L and 9.1 (+/- 2.5) X 10(-7) mol/L, respectively. These results suggest that BN 52021 has potential as an anti-inflammatory agent in conditions associated with PAF-induced accumulation of neutrophils and eosinophils.

Albuterol↗
PubMed1989

HLA class II restriction specificity of Dermatophagoides spp. reactive T lymphocyte clones that support IgE synthesis.

The results of recent experiments investigating the restriction specificity of cross-reactive, or Dermatophagoides farinae-specific, T cell clones isolated from an atopic individual with perennial rhinitis are reviewed. The restriction specificity was examined using serological inhibition, allogeneic presenting cells and murine fibroblasts expressing HLA-D region products. Although serological inhibition studies suggested that DR class II proteins were the major restriction elements used, the patterns of recognition observed with the allogeneic cell panel were complex, generally failing to correlate with the serologically defined MHC class II specificities. Analysis of the restriction patterns indicated that the majority of the T cell clones were restricted by DR beta III gene products and this was confirmed using murine fibroblasts expressing DRw52. DR beta I gene products functioned as restriction elements in the recognition of house dust mite allergen by the other clones. In an in-vitro model of allergen-dependent IgE synthesis, both DR beta I and DR beta III class II restricted T cells could be shown to provide functional help for IgE synthesized by autologous B cell-enriched populations.

Animals↗
PubMed1989

T lymphocytes in allergen-induced late-phase reactions and asthma.

We have studied a number of aspects of the interrelationship between T lymphocytes and allergic inflammation. Using monoclonal antibodies and immunocytochemistry we have observed significant infiltration by CD3+/CD4+ T lymphocytes together with evidence of T cell activation in the allergen-induced late-phase skin reaction in human atopic subjects. These changes were accompanied by eosinophil infiltration and activation. Activated T cells were also detected in the blood of patients with acute severe asthma. The role of T lymphocytes in granulocyte chemotaxis and activation was also explored, using recombinant human lymphokines, and we have identified and characterized two lymphokines which have specific effects upon neutrophils.

Acute Disease↗
PubMed1989

Clonal analysis of the cellular immune response to the house dust mite Dermatophagoides farinae.

A panel of human CD4+ T cell clones specific for the house dust mite was isolated from an atopic individual with perennial rhinitis. Soluble antigen specificity was defined using proliferation assays and subsequently the antigenic determinants recognized by some of these clones were mapped using nitrocellulose immunoblots of fractionated Dermatophagoides spp. Both cross-reactive and species-specific T cell clones were identified and in some instances their specificity could be mapped to the serologically defined Der f I, Der p I and Der f II allergens. In comparison, the serum antibody response showed additional specificity for Der f III. The antigen recognition by six of these clones was found to be restricted by HLA-DR gene products.

Allergens↗
PubMed1989

Leukocytes and mediators in bronchoalveolar lavage during allergen-induced late-phase asthmatic reactions.

We have measured the total and differential cell counts, histamine, leukotriene (LT) B4 and LTC4, immunoglobulins, complement (C3), eosinophil-derived basic proteins, and monocyte complement rosettes in bronchoalveolar lavage (BAL) 6 h after challenge with either antigen or diluent control in seven patients with antigen-induced single early reactions, and seven with dual (early and late phase) reactions. In both groups, the total cell counts in BAL were similar, irrespective of whether they were challenged with antigen or diluent. However, in the late-phase responders (LPR), there were significant increases in lymphocytes, neutrophils, and eosinophils (p less than 0.05), and significant decreases in the percentage of lung mast cells (p less than 0.05). The eosinophil major basic protein and eosinophil-derived neurotoxin increased in four of five subjects with dual responses and in the majority of single early responders (SER). BAL histamine concentrations increased in five of seven patients with dual responses. There were no consistent changes in LTB4 concentrations in either the LPR or the SER between diluent and antigen days, but a small but significant increase in LTC4 was observed in the LPR. Concentrations of IgG, IgA, IgM, IgE, C3, and albumin did not differ significantly. The percentage of monocyte complement rosettes also increased significantly (p less than 0.05) in LPR, but not in SER. These findings support the hypothesis that eosinophils and their products play a role in tissue injury in LPR and that eosinophil infiltration may be associated with macrophage activation.

Adolescent↗
PubMed1989

Bronchial biopsies in asthma. An ultrastructural, quantitative study and correlation with hyperreactivity.

Little is known of the structural changes in mild asthma. We have studied the light and electron microscopic structure of lobar bronchial biopsies taken at fiberoptic bronchoscopy from 11 atopic asthmatics, four of whom were symptomatic and seven of whom were asymptomatic. The former and three of the latter had bronchial hyperresponsiveness to methacholine (PC20 less than 4 mg/ml). Quantitative comparisons were made with biopsies from ten control subjects with normal airway reactivity; five had hay fever and five were nonatopic healthy volunteers. Complete absence of surface epithelium was found in three cases of symptomatic asthma, and stratified squamous epithelium was present in the fourth. A biopsy from one of the healthy control subjects had also lost its surface epithelium. The degree of epithelial loss in all subjects correlated with the degree of airway reactivity (rs = 0.67, p less than 0.001). The reticular lamina of the epithelial basement membrane showed a trend toward thickening in the seven hyperreactive asthmatics (p less than 0.001: median test). There was a tendency to high numbers of inflammatory cells in the lamina propria, but not in the submucosa, of asthmatics, but the differences between groups did not achieve statistical significance. There were significant alterations (px2 less than 0.001) in the proportions of each type of inflammatory cell found in the lamina propria and submucosa of symptomatic asthmatics: an increase of irregularly shaped lymphocytes contributed most to the observed alteration. Where surface epithelium was present, intraepithelial lymphocytes formed the major proportion of intraepithelial "migratory" cells: 64% in normal control subjects, 78% in subjects with hay fever, and 87% in asymptomatic asthmatics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The effect of nedocromil sodium on human eosinophil activation.

Nedocromil sodium inhibited the increase in eosinophil activation (measured by IgG- and complement-dependent cytotoxicity assays) induced by platelet activating factor (PAF). Inhibition of the upregulation in eosinophil effector function by nedocromil sodium was dose-dependent (optimal at 10(-7) mol/L) and paralleled that produced by a specific PAF antagonist, BN 52021. In addition, preliminary data suggest that nedocromil sodium can inhibit the increase in IgG-dependent release of LTC4 from human eosinophils after stimulation with the synthetic tripeptide, formyl-methionyl-leucyl-phenylalanine (fMLP). These data support our previous hypothesis that part of the mode of action of nedocromil sodium may be due to its ability to directly block the chemotactic factor-induced enhancement of inflammatory cell activity.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Inflammatory cells in bronchial asthma.

A diagrammatic representation of the interactions between mediators of hypersensitivity and leukocytes in early, late-phase, and ongoing asthma is shown in Figure 1. Early phase or immediate reactions are largely the result of bronchoconstriction consequent to the release of mediators such as histamine, PGD2, LTC4/D4, and PAF. The principal mediator cell (MC) is the mast cell (although other IgE receptor-bearing cells such as the macrophage, eosinophil, and platelet might also be involved in this immediate response). The stimulus for mediator cell activation may be either immunologic (IgE-dependent) or nonimmunologic (i.e., changes in osmolarity as a result of the respiratory water loss associated with exercise-induced asthma). Late-phase reactions appear to be a consequence of infiltration with neutrophils (N), eosinophils (E), and macrophages (M phi). These cells are recruited and activated either by mast cell-associated chemotactic factors [such as LTB4, PAF, the eosinophil chemotactic factor of anaphylaxis (ECF-A), or high-molecular weight neutrophil chemotactic activity (NCA (HMW))] and/or "lymphokines" derived from T-helper cells (TH) which have been stimulated by antigen processed by the antigen-processing cells (APC). These mononuclear cell interactions are under the control of regulatory T cells [T suppressor (TS) cells] and it is speculated that the availability of these subsets may determine the magnitude of the late-phase response. Lymphokines and monokines which selectively activate neutrophils, eosinophils, and monocytes include LIF, EAF, and IFN-gamma, respectively. Macrophage-derived tumor necrosis factor (TNF) also amplifies the inflammatory response by its capacity to enhance eosinophil cytotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗
PubMed1989

An in vitro model of allergen-dependent IgE synthesis by human B lymphocytes: comparison of the response of an atopic and a non-atopic individual to Dermatophagoides spp. (house dust mite).

An allergen-dependent in vitro model of immunoglobulin E (IgE) synthesis by human B cells is reported. Using this model, it is demonstrated that polyclonal T cells and CD4+ Dermatophagoides spp. (house dust mite)-specific T-cell clones derived from an atopic, house dust mite (HDM)-allergic individual are able to support IgE synthesis by autologous B cells. The helper activity was interleukin-4 (IL-4) dependent as only cloned T cells expressing detectable mRNA for IL-4 were able to induce IgE synthesis without the addition of exogenous IL-4. Peripheral and cloned T cells reactive with HDM could also be identified from a non-atopic individual but neither population was able to support IgE production even in the presence of exogenous IL-4.

Allergens↗