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Biomedical subjects

O Cromwell

Publications and source records attributed to O Cromwell.

At least 37 records · Page 2Linked to original sources

Reactivity of T cells with grass pollen allergen extract and allergoid.

BACKGROUND: Successful allergen-specific immunotherapy is achieved with progressively increasing doses of allergen or allergoid. In order to gain further insight into the mechanism of action of allergoids several in vitro investigations were conducted. METHODS: Peripheral blood mononuclear cells (PBMC) from grass pollen allergic and nonallergic subjects were stimulated with either grass pollen extract or allergoid and the proliferation and cytokine production (IL-5, IFN-gamma) were measured. Similar investigations were performed with Phl p 5-specific T cell lines (TCL) and clones (TCC). Dendritic cells and PBMC were compared in terms of their relative efficacies as antigen-presenting cells. RESULTS: Both allergen and allergoid induced proliferation and Th2 and Th1 cytokine synthesis by PBMC of allergic subjects, whereas PBMC of nonallergic subjects did not produce IL-5. The maximum level of IL-5 was obtained with a lower concentration than was necessary for maximal IFN-gamma production. Higher stimulation doses of allergen and allergoid shifted the cytokine profiles towards a Th1 phenotype. TCL and TCC clearly showed reactivity with both allergen and allergoid when using autologous PBMC for antigen presentation, but compared with the native allergen the reactivity of the allergoid was reduced with most of the TCC. Using dendritic cells for antigen presentation a pronounced increase of stimulation of the TCC especially for the allergoids becomes obvious. CONCLUSION: In common with grass pollen allergen the corresponding allergoids possess a strong allergen-specific T cell-stimulating capacity. However, the degree of T cell stimulation by the allergoid seems to be dependent on the type of the antigen-presenting cell. Both, allergen and allergoid, can modulate T cell responses in a dose-dependent manner.

Allergens↗

Detection and quantification of group 4 allergens in grass pollen extracts using monoclonal antibodies.

BACKGROUND: Grass pollen extracts are complex mixtures consisting of different major allergenic and non-allergenic components. Phl p 4 is an important allergen, because more than 75% of grass pollen allergic patients produce specific IgE antibodies against group 4 allergens. OBJECTIVE: This study was designed to investigate the specificity of monoclonal antibodies (MoAbs) produced against Phl p 4 and to verify the presence of group 4-like proteins in different grass pollen. Furthermore the usefulness of MoAbs for quantification of group 4 allergens was studied. METHODS: Group 4 analogues were investigated by immunoblotting and ELISA inhibition using three MoAbs. The specificity of antibodies was studied using isolated group 1 and group 5 allergens. Quantification of group 4 allergen was achieved by a two-site solid-phase ELISA. Phl p 4 was purified from whole pollen extract by chromatographic or electrophoretic techniques and used as standard. RESULTS: The MoAbs studied bound strongly to proteins from timothy grass pollen extract at a mw of 55 kDa and a pI of 9.0-9.3. Phl p 4 homologes with similar mw were detected in Dactylis glomerata, Festuca pratensis, Holcus lanatus, Poa pratensis, Lolium perenne. Epitope mapping showed that all three MoAb recognized unrelated regions on Phl p 4. A two-site binding ELISA using MoAbs was developed for determination of Phl p 4 in Phleum pratense extracts. The method was able to evaluate group 4 in mass units with a working range between 150 and 2000 ng/mL. The absolute amounts of group 4 in extracts of several grasses varied considerably but was always-less than 1% of the total protein. CONCLUSION: Group 4 homologes are present in the various grass extracts but to different extents. The group 4 ELISA could be very useful as a additional tool for providing information concerning the composition of grass pollen extracts.

Allergens↗

Mapping of T-cell epitopes of Phl p 5: evidence for crossreacting and non-crossreacting T-cell epitopes within Phl p 5 isoallergens.

BACKGROUND: Group 5 allergens represent major grass pollen allergens because of their high sensitization indices. The identification of T-cell epitopes of these allergens is a prerequisite for the design of immunotherapeutic strategies based on peptide vaccination or modified allergens with conserved T-cell epitopes. OBJECTIVE: This study was undertaken to determine T-cell epitopes on Phl p 5 major pollen allergen of timothy grass (Phleumn pratense). METHODS: T-cell lines (TCLs) and T-cell clones (TCCs), specific to Phl p 5, were established from the peripheral blood of 18 patients allergic to grass pollen. All TCCs were mapped for epitope specificities using 178 overlapping dodecapeptides representing the primary structures of two isoforms of Phl p 5 (Phl p 5a and Phl p 5b). Phenotype and cytokine production profiles of TCCs were tested. Selected TCCs were analysed for HLA class II restriction. RESULTS: A total of 82 TCCs were isolated. All TCCs displayed the helper cell (TH) phenotype. Their reactivity with two recombinant expressed isoforms of Phl p 5a and Phl p 5b was heterogeneous. The epitope specificity of the TCCs was then revealed. Nineteen T-cell epitopes could be identified on Phl p 5. Eighty-one percent of mapped TCCs recognized three T-cell reactive regions on the Phl p 5 allergen. Some TCCs were reactive with isoepitopes presenting on Phl p 5a as well as Phl p 5b. Allergen-specific stimulation induced a TH0-like type of cytokine production in 25 of 50 TCCs. Almost all TCCs secreted high concentrations of interleukin-13. CONCLUSION: Phl p 5, a major grass pollen allergen, contains several T-cell epitopes. Some epitope regions were recognized by several patients. Epitope recognition pattern could not be correlated with special HLA class II haplotypes. T-cell stimulating isoepitopes were found at corresponding regions of Phl p 5a and Phl p 5b isoforms.

Adult↗

Immunotherapy with an alum-adsorbed Parietaria-pollen allergoid: a 2-year, double-blind, placebo-controlled study.

A double-blind, placebo-controlled study was performed in order to confirm the safety, suitability, and efficacy of an alum-adsorbed Parietaria judaica-pollen allergoid, Allergovit, for allergen-specific immunotherapy. Parietaria pollen is an important cause of pollinosis, particularly in the Mediterranean zone, where it may be encountered for up to 8-9 months of the year. It is an aggressive allergen, and the doses tolerated during immunotherapy are less than those achieved with grass pollen. This factor increases the desirability of using therapeutic preparations with minimal IgE-binding activity, such as allergoids, in order to reduce the risk of side-effects and enable patients to tolerate a higher dose of allergen, thereby increasing the chances of successful specific immunotherapy. Forty patients with rhinitis and/or asthma were allocated at random to active- or placebo-treatment groups at the beginning of the study. All patients received the active preparation during the second year of the study. Immunotherapy was well tolerated by all patients and the incidence of side-effects was low. Treatment resulted in significant reductions in specific cutaneous reactivity and increases in nasal tolerance. A progressive improvement in nasal inspiratory peak flow in association with the immunotherapy indicated a reduction in nasal inflammation. These objective assessments of efficacy endorsed the results from the patients' diary cards, which indicated significant improvements in symptoms and reductions in the use of medication. The immunologic activity of the therapeutic preparation was demonstrated by the induction of a significant specific-IgG antibody response, with increases in IgG4 during the second year of treatment. We conclude that the safety and efficacy of immunotherapy with the Parietaria allergoid make it suitable for consideration in the treatment of patients with Parietaria-pollen-induced rhinitis or asthma.

Adolescent↗

Application of reversed-phase high-performance liquid chromatography in the purification of major allergens from grass pollen.

Group 1 and 5 allergens of different grasses possess similar physicochemical parameters (molecular weight, pI) and therefore separation with conventional chromatographic methods (gel filtration, ion exchange chromatography) is difficult or impossible to achieve. In this paper we describe the isolation of biologically active group 1 and 5 allergens from extracts of Lolium perenne and Phleum pratense by means of reverse phase chromatography on HPLC. The chromatograms showed very different retention times for group 1 (Rt 19.1-20.5 min) and group 5 (Rt 24.3-26.3 min) containing fractions. In addition, this technique is suitable for the separation of group 5 allergens into 5a and 5b subgroups and for the estimation of the amounts of allergen (groups 1 and 5) in the different extracts.

Allergens↗

In vitro investigation of cross-reactivity between birch and ash pollen allergen extracts.

Allergenic cross-reactivity between members of the Fagales family (birch, alder, hazel, and beech) and between members of the Oleaceae family (ash, olive, lilac, and privet) is well known, but little is known about possible cross-reactivity between these two groups of trees, in particular between birch and ash, both of which flower in the spring. Various immunochemical methods including RAST inhibition, Western blot, and Western blot inhibition have been used in this study to show that there is partial cross-reactivity between birch and ash pollens. Enzyme allergosorbent test measurements were performed on sera from 35 patients with hay fever in spring by using birch and ash pollen allergen disks. The major allergen of birch, Bet v 1, was readily detectable in the birch pollen extract, but a homologous allergen in the ash pollen extract was barely detectable. Common allergens could be determined in the high molecular weight region. Ash pollen should be included in diagnostic procedures for spring pollinosis and should be considered for use in specific immunotherapy.

Adolescent↗

Characterization of major allergens of Parietaria officinalis.

The major allergens of Parietaria officinalis were characterized with a panel of nine monoclonal antibodies (mAbs). The binding of mAbs and patients' IgE in Western blots revealed two proteins with similar molecular weights in the range of 8-10 kD. Analysis of the mAb-binding patterns in Western blots of P. officinalis extract under reducing and nonreducing conditions allows the mAbs to be divided into three different groups. mAbs of group I recognize the higher-molecular-weight component (9.4 kD), mAbs of group II recognize the lower component (8.8 kD) and mAbs of group III recognize both proteins. A comparable mAb-binding pattern was observed with Western blots of Parietaria judaica. The mAbs were used for affinity purification of the corresponding proteins from a P. officinalis extract. The purified proteins obtained with mAbs of group I-III inhibit the binding of patients' IgE (serum pool) to a high degree, indicating that they posses the major IgE-reactive epitopes. The affinity-purified proteins were subjected to SDS-PAGE, blotted and immunologically stained by mAb binding. The results confirmed those obtained with the complete extracts. The N-terminal amino acid sequences of the blotted proteins were analyzed. The sequences of all the proteins contained highly conserved regions: GGVV (positions 4-7) and MPPLL (positions 11-15), alternating with highly variable regions (positions 1-3 for group II and 8-10 for group I). A specific group I sequence appears to be at position 1-3 with the amino acids APA and a specific group II sequence appears to be at position 8-10 with the amino acids GAL. It is possible that the two similar proteins are isoforms of Par o 1.

Allergens↗

Seasonal occupational asthma in an agricultural products merchant--a case report.

A 52-year-old agricultural products merchant reported mild occupational asthma and rhinitis throughout the year, with severe asthma from February to May. He had been exposed to various substances, particularly grain, insecticides, fungicides, and fertilizers over 35 years. We identified a castor-bean-containing fertilizer as the cause of the disease by skin prick test and bronchial provocation test. Specific IgE against castor bean was detected by enzyme allergosorbent test, and proteins with mol. mass of less than 14.4 kDa and masses of 15.5, 29.5, and 30.5 kDa were identified as allergens by Western blot analysis. The seasonal character of symptoms could be explained by a more frequent use of the fertilizer during spring. Six months after avoidance of the allergen, the patient reported chronic bronchitis without asthma. Occupational allergy to castor bean should be considered in subjects with seasonal asthma and exposure to "natural" fertilizers.

Asthma↗

Adhesion to fibronectin primes eosinophils via alpha 4 beta 1 (VLA-4).

Human peripheral blood eosinophils adhered specifically to microtitre plates coated with plasma fibronectin (Fn) in a dose- and time-dependent fashion. Adhesion was optimal at 60 min at a concentration of 100 micrograms/ml. Adherence to Fn was up-regulated by platelet-activating factor (PAF; optimum concentration of 10(-6) M) and was significantly inhibited by a polyclonal anti-Fn antibody (P < 0.05). The following evidence suggested that eosinophil adhesion to Fn was mediated by alpha 4 beta 1: (1) eosinophil adherence to Fn was not inhibited by an Arg-Gly-Asp-Ser (RGDS) synthetic peptide; (2) there was a dose-dependent adherence of eosinophils to microtitre plates coated with the 40,000 MW proteolytic fragment of Fn that contains the CS-1 alpha 4 beta 1 binding region, whereas adherence to the 120,000 MW chymotryptic fragment of Fn, which contains the RGD-dependent binding site, was weak and only observed at high concentrations (> 250 micrograms/ml); (3) significant inhibition of eosinophil adherence to Fn was achieved by monoclonal antibodies (mAb) against the alpha chain of VLA-4 but not by a mAb against CD45 or a mouse myeloma antibody as negative controls. After adhesion to Fn, eosinophils were investigated for their capacity to release leukotriene C4 in response to stimulation with a suboptimal concentration of calcium ionophore (2 x 10(-6) M). Significant enhancement of release was detected with Fn-coated plates but not with the control bovine serum albumin (BSA) (P < 0.01). Furthermore, this enhancement was significantly inhibited by the alpha 4 beta 1 mAb HP2/1 (P < 0.05) but not by an anti-CD45 mAb. From these studies we conclude that (1) alpha 4 beta 1 (VLA-4) integrin is a major receptor for Fn on human eosinophils and (2) adhesion to Fn may prime eosinophils for mediator release during allergic inflammation.

Antibodies↗

Expression of endothelial and leukocyte adhesion molecules interacellular adhesion molecule-1, E-selectin, and vascular cell adhesion molecule-1 in the bronchial mucosa in steady-state and allergen-induced asthma.

BACKGROUND: Interactions between cell adhesion molecules and their ligands are an integral part of inflammatory processes and may have direct relevance to the pathology of asthma. METHODS: Immunostaining with antibodies to cell adhesion molecules was performed on bronchial biopsy specimens from persons with intrinsic and extrinsic asthma, normal nonasthmatic control subjects, and patients with asthma after allergen challenge. RESULTS: There was constitutive expression of intercellular adhesion molecule-1 (ICAM-1), E-selectin and vascular cell adhesion molecule-1 (VCAM-1) in patients with intrinsic and extrinsic asthma and in control subjects. Compared with control subjects, ICAM-1 and E-selectin staining in the submucosa was greater in the intrinsic asthmatic group for intensity (p < 0.02, p < 0.05) and extent (p < 0.01, p < 0.05) of staining, respectively. No differences were observed between patients with extrinsic asthma and normal control subjects, and VCAM-1 expression did not differ among the groups. Epithelial expression of ICAM-1 was more frequent in patients with asthma compared with normal control subjects (p < 0.05). Compared with diluent challenge, bronchial biopsy specimens obtained 24 hours after allergen challenge revealed no significant differences in intensity or extent of staining for ICAM-1, E-selectin, or VCAM-1. After allergen challenge, the intensity and extent of both VCAM-1 and ICAM-1 expression correlated significantly with the number of eosinophils (cells positive for major basic protein). Epithelial ICAM-1 expression was more frequently observed after allergen challenge than after diluent challenge (p < 0.02). CONCLUSIONS: The data suggest a complex pattern of regulation for ICAM-1, E-selectin, and VCAM-1 in vivo, where they may reflect the degree of ongoing inflammation in asthma.

Adult↗

Interleukin-8 is a chemo-attractant for eosinophils purified from subjects with a blood eosinophilia but not from normal healthy subjects.

Interleukin-8 (IL-8), a pro-inflammatory cytokine with potent neutrophil chemotactic activity, was studied for its effect on eosinophil migration responses, in vitro. Normal density eosinophils were isolated from healthy, non-atopic subjects (<0.35 x 10(9) eosinophils/l) and individuals with various diseases associated with a blood eosinophilia (range 0.56 x 10(9)-12.2 x 10(9) eosinophils/l). IL-8 produced a dose-dependent migrational response for eosinophils from subjects with an eosinophilia, optimal at 10(-8) M (P < 0.01) and the major component of the migrational response was chemokinesis. On a molar basis, IL-8 (EC50 approximately 10(10) M) was 100-fold more potent than platelet activating factor (PAF), although a comparison of the migrational responses showed that at optimal concentrations IL-8 (10(-8) M) produced only 30% maximal responses stimulated by PAF (10(-6) M). In contrast, IL-8 tested over a wide concentration range had a negligible effect on eosinophils from normal subjects. A direct correlation between the total blood eosinophil counts for all subjects and the absolute magnitude of the migrational response to IL-8 (r = 0.727, P < 0.01 at 10(-8) M), PAF (r = 0.551, P < 0.03 at 10(-6) M) and N-formyl-methionyl-leucyl-phenylalanine (fMLP) (r = 0.689, P < 0.02 at 10(-8) M), suggested that heightened eosinophil migrational responses to inflammatory mediators may arise as a consequence of in vivo priming mechanism(s) associated with the development of an eosinophilia. In this regard, eosinophils derived from human cord blood mononuclear cells cultured in the presence of eosinophilopoietic cytokines IL-3 and IL-5, produced migrational responses to IL-8 and PAF, that were comparable with that of eosinophils from eosinophilic subjects. Furthermore, incubation of eosinophils from normal donors with IL-5 (optimal concentration 10(-9) M), significantly enhanced the subsequent migrational responses to both IL-8 (10(-8) M, P < 0.01) and PAF (10(-8) M, P < 0.05). Therefore, the increased responsiveness of eosinophils from eosinophilic subjects may reflect in vivo priming by IL-5 and this phenomenon may contribute partly to the mechanism(s) by which eosinophils preferentially accumulate at sites of allergic inflammation.

Cells, Cultured↗

The membrane fusion events in degranulating guinea pig eosinophils.

We have investigated the granule fusion events associated with exocytosis in degranulating peritoneal guinea pig eosinophils by time-resolved patch-clamp capacitance measurements using the phase detector technique. Intracellular stimulation with micromolar calcium and GTP gamma S induces a 2- to 3-fold capacitance increase. The main phase of the capacitance increase occurs after a delay of 2-7 minutes and is composed of well-resolved capacitance steps. The number of steps is very close to the number of crystalloid granules contained in a resting cell and the step size distribution with a peak at 9 fF is in excellent agreement with the granule size distribution determined by electron microscopy. The individual granules thus fuse sequentially with the plasma membrane. The stepwise capacitance increase is frequently preceded by an apparently continuous capacitance increase which consists of steps smaller than 4 fF, indicating exocytosis of small vesicles as distinct from crystalloid-containing granules. In some cases the time course of the opening of individual fusion pores could be recorded, and this revealed metastable conductance states below 300 pS but random fluctuations at higher conductance levels. This behaviour suggests that the small fusion pore might be a protein structure similar to an ion channel, which becomes a continuously variable lipid pore at higher conductances. In some cells a significant capacitance decrease was observed which is apparently continuous, suggesting a process of membrane uptake by endocytosis of small vesicles.

Animals↗

Interleukin-5 selectively enhances the chemotactic response of eosinophils obtained from normal but not eosinophilic subjects.

We have attempted to determine whether interleukin-5 (IL-5), a cytokine that selectively affects eosinophil (as opposed to neutrophil) differentiation and activation, also modulates eosinophil migrational responses. Using a modified Boyden chemotaxis assay, IL-5, IL-3, and granulocyte-macrophage colony-stimulating factor (GM-CSF) gave a weak locomotory response for eosinophils from normal nonatopic subjects (optimal at 10(-11), 10(-8), and 10(-9) mol/L, respectively), but not for eosinophils from subjects with an eosinophilia associated with asthma and/or allergic rhinitis. In contrast, IL-5 and IL-3 had no effect on neutrophils, while GM-CSF was chemotactic for neutrophils over a limited concentration range, optimal at 10(-8) mol/L. When eosinophils from normal subjects were incubated with IL-5 (10(-9) mol/L), the locomotory response to platelet-activating factor (PAF; 10(-8) mol/L, P less than .05), leukotriene B4 (LTB4; 10(-6) mol/L, P less than .01), and N-formyl-methionyl-leucyl-phenylalanine (FMLP; 10(-8) mol/L, P less than .01) was significantly enhanced. The percentage enhancement of eosinophil locomotion by IL-5 was greater for eosinophils from normal as compared with subjects with an eosinophilia associated with asthma (P less than .05 for PAF and LTB4; P less than .01 for FMLP). Preincubation of eosinophils from normal subjects with IL-5 (10(-9) mol/L) attenuated the subsequent locomotory response to IL-5 (10(-12) and 10(-11) mol/L, P less than .05). Therefore, the observed refractoriness of eosinophils from eosinophilic subjects to both directional migratory and priming effects of IL-5 in vitro, may reflect a deactivation process resulting from prior exposure in vivo. The selective priming of eosinophil but not neutrophil locomotion by IL-5 suggests that this cytokine may play a significant role in the preferential accumulation of eosinophils at sites of allergic inflammation.

Asthma↗

Identification on receptors for leukotriene B4 expressed on guinea-pig peritoneal eosinophils.

We have recently reported that guinea-pig eosinophil chemotactic factor of anaphylaxis (ECF-A), an activity present in diffusates from antigen-challenged sensitized lung, is largely accounted for by leukotriene B4 (LTB4) and to a lesser extent 8(S)15(S)-dihydroxy 5,9,11,13 (Z,E,Z,E) eicosatetraenoic acid. We characterized cell surface receptors for LTB4 on guinea-pig eosinophils in order to demonstrate an association between receptor occupancy and eosinophiliotactic activity of guinea-pig ECF-A. Equilibrium binding studies showed that peritoneal eosinophils bound [3H]LTB4 in a cell concentration and time-dependent fashion. The binding was saturable and specific for LTB4 as other eosinophil chemoattractants, i.e. platelet-activating factor (PAF) and 8(S)15(S)-diHETE, were unable to displace significant amounts of [3H]LTB4. In addition the binding was readily reversed by the LTB4 receptor antagonist LY 255283 (Ki 4.30 nM). Scatchard plot analysis revealed two discrete populations of binding sites, high affinity (Kd1 = 0.30 nM; Bmax = 900 sites/cell) and low-affinity sites (Kd2 = 140 nM; Bmax = 60,000 sites/cell). The major migratory component of LTB4-stimulated eosinophil locomotion was chemotaxis, optimal at 1 x 10(-7) M (P < 0.01) with EC50 value of 3 x 10(-9) M. A comparison of the profile of arachidonic acid metabolism by RP-HPLC analysis showed that following stimulation with calcium ionophore (A23187) guinea-pig eosinophils preferentially synthesized LTB4 (10 ng/10(6) cells) while in contrast human eosinophils synthesized LTC4 (10 ng/10(6) cells). Therefore our data show that guinea-pig eosinophils express both high- and low-affinity receptors for LTB4 and that the chemotactic response to this mediator may be mediated by ligation of the high-affinity binding site. Furthermore guinea-pig peritoneal eosinophils can synthesize LTB4, a mediator which constitutes > 60% of guinea-pig ECF-A.

Animals↗

Expression and generation of interleukin-8, IL-6 and granulocyte-macrophage colony-stimulating factor by bronchial epithelial cells and enhancement by IL-1 beta and tumour necrosis factor-alpha.

We have tested the hypothesis that the bronchial epithelium has the capacity to generate and release cytokines that could contribute to inflammatory events associated with inflammatory lung diseases. Messenger RNA (mRNA) for interleukin-6 (IL-6), IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) was identified in human bronchial epithelial cell primary cultures, characterized on the basis of staining for cytokeratin, using both in situ hybridization and Northern blotting. Using in situ hybridization we have shown that the majority of the cells expressed mRNA for IL-6 and IL-8, whereas fewer than 20% of cells expressed message for GM-CSF. The numbers of cells expressing message were increased by culture with tumour necrosis factor-alpha (TNF-alpha) (20 ng/ml, 24 hr). These observations were substantiated by Northern blotting, which showed that both TNF-alpha and IL-1 beta were able to induce a dose-dependent increase in IL-8-specific mRNA. Immunoreactive IL-6 and GM-CSF were detected and quantified in the culture supernatants by ELISA, and IL-8 by radioimmunoassay. The levels of immunoreactivity were increased by incubation of epithelial cells with either IL-1 beta or TNF-alpha for 24 hr. A transformed tracheal epithelial cell line (9HTEo-) expressed mRNA for IL-6, IL-8 and GM-CSF but, whereas levels of immunoreactive IL-6 in culture supernatants were comparable with those in primary cell cultures, levels of IL-8 were low and GM-CSF trivial. These observations indicate that the bronchial epithelium has the potential to be a major source of IL-8 and a number of other cytokines, and that production can be amplified substantially by IL-1 beta and TNF-alpha. The bronchial epithelium is ideally situated to modulate inflammatory and immunological events in and around the airways, and these observations suggest that it could contribute to promote and sustain inflammatory and immunological processes in inflammatory lung diseases such asthma.

Blotting, Northern↗