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R Valenta

Publications and source records attributed to R Valenta.

At least 37 records · Page 2Linked to original sources
PubMed2003

Possible modes of allergen-specific sensitization and boosting in an atopic child.

Several studies document that allergen-specific IgE levels are boosted by allergen contact via the respiratory tract in allergic patients. Only few data are available on whether other routes of allergen contact have an influence on systemic IgE responses. We report the case of a boy who developed egg allergy after heavy consumption of eggs by the mother during pregnancy and breast feeding. In contrast to other children who outgrow egg allergy during the first years of life, the boy experienced further dramatic increases in hen egg-specific IgE antibodies after prolonged consumption of ostrich eggs containing cross-reactive allergens. IgE antibodies to most of the important respiratory allergens remained either low or not detectable. The dramatic increases in hen egg-specific IgE antibody levels after oral intake of allergens demonstrate that systemic IgE responses in allergic patients can be strongly boosted by allergen contact via routes other than the respiratory tract.

Allergens↗
PubMed2003

Identification of oilseed rape (Brassica napus) pollen profilin as a cross-reactive allergen.

BACKGROUND: Major allergens of oilseed rape (OSR) pollen with molecular weights of 6/8, 14 and between 27 and 69 kD have been described. The aim of the present study was to further characterize the 14-kD allergen. METHODS: The 14-kD protein was purified from OSR pollen extracts by poly-(L-proline) (PLP)-Sepharose affinity chromatography and characterized immunologically by means of allergic patients' IgE antibodies, profilin-specific rabbit antisera, Western blot and ELISA inhibition using recombinant birch profilin (rBet v 2), and skin prick testing. RESULTS: By PLP affinity chromatography, OSR pollen profilin was purified as a single protein of 14.5 kD and further identified as a profilin by three polyclonal rabbit antisera raised against ragweed and tobacco pollen profilin and the C-terminus of birch profilin. IgE binding of a human serum pool (n = 15) and four profilin-reactive sera to nitrocellulose-blotted OSR profilin was completely inhibited by 1 microg/ml rBet v 2 (birch profilin). Reciprocal ELISA inhibition using increasing concentrations of rBet v 2 and purified OSR profilin, respectively, showed that rBet v 2 strongly inhibits antibody binding to OSR profilin, whereas almost 100 times the amount of OSR profilin was needed to inhibit IgE binding to rBet v 2. Skin prick tests were positive (wheal >/=3 mm) with 5 microg/ml rBet v 2 in all three patients tested, and with OSR profilin in two patients at a concentration of 50 microg/ml. CONCLUSIONS: OSR pollen profilin shares IgE and IgG epitopes with Bet v 2 and other plant profilins and may represent a potentially relevant allergen for profilin-sensitized patients.

Blotting, Western↗
PubMed2002

Recombinant fish parvalbumins: Candidates for diagnosis and treatment of fish allergy.

Fish and fish products represent one of the most important causes of IgE-mediated food hypersensitivity. In sensitized individuals contact with and consumption of fish can lead to severe health problems, ranging from urticaria and dermatitis to angiedema, diarrhoea, asthma and, at worst, systemic anaphylactic reactions and death. Parvalbumin, a small calcium-binding protein present in the muscles of vertebrates, was identified as the major fish allergen. We describe the isolation and characterization of cDNA clones coding for carp parvalbumin by IgE immunoscreening of a carp muscle expression library. These clones will be the basis for the production of recombinant carp parvalbumin, a useful tool for in vitro and in vivo diagnosis of fish allergy.

Allergens↗
PubMed2002

The allergen profile of ash (Fraxinus excelsior) pollen: cross-reactivity with allergens from various plant species.

BACKGROUND: Ash, a wind-pollinated tree belonging to the family Oleaceae, is distributed world-wide and has been suggested as a potent allergen source in spring time. OBJECTIVE: The aim of this study was to determine the profile of allergen components in ash pollen in order to refine diagnosis and therapy for patients with sensitivity to ash pollen METHODS: The IgE reactivity profile of 40 ash pollen-allergic patients was determined by immunoblotting. Antibodies raised to purified pollen allergens from tree and grass pollens were used to identify cross-reactive structures in ash pollen extract. IgE immunoblot inhibition studies were performed with recombinant and natural pollen allergens to characterize ash pollen allergens and to determine the degree of cross-reactivity between pollen allergens from ash, olive, birch, grasses and weeds. RESULTS: The allergen profile of ash pollen comprises Fra e 1, a major allergen related to the major olive allergen, Ole e 1, and to group 11 grass pollen allergens, the panallergen profilin, a two EF-hand calcium-binding protein, a pectinesterase-like molecule and an allergen sharing epitopes with group 4 grass pollen allergens. Thus, the relevant allergens of ash are primarily allergens that share epitopes with pollen allergens from other tree, grass and weed species. CONCLUSIONS: Allergic symptoms to ash pollen can be the consequence of sensitization to cross-reactive allergens from other sources. The fact that ash pollen-allergic patients can be discriminated on the basis of their specific IgE reactivity profile to highly or moderately cross-reactive allergens has implications for the selection of appropriate forms of treatment.

Adolescent↗
PubMed2002

Molecular and immunological characterization of a novel timothy grass (Phleum pratense) pollen allergen, Phl p 11.

BACKGROUND: Allergy to grass pollen is typically associated with serum IgE antibodies to group 1 and/or group 5 allergens, and additionally often to one or several less prominent allergens. Most of the grass pollen allergens identified to date have been characterized in detail by molecular, biochemical and immunological methods, timothy grass being one of the most thoroughly studied species. However, a 20-kDa allergen frequently recognized by IgE antibodies from grass pollen allergics has so far escaped cloning and molecular characterization. OBJECTIVE: To clone and characterize the 20 kDa timothy grass pollen allergen Phl p 11. METHODS: Phl p 11 cDNA was cloned by PCR techniques, utilizing N-terminal amino acid sequence obtained from the natural allergen. Phl p 11 was expressed as a soluble fusion protein in Escherichia coli, purified to homogeneity and used for serological analysis and to study Phl p 11 specific induction of histamine release from basophils and skin reactivity in sensitized and control subjects. RESULTS: Phl p 11 cDNA defined an acidic polypeptide of 15.8 kDa with homology to pollen proteins from a variety of plant species and to soybean trypsin inhibitor. The sequence contained one potential site for N-linked glycosylation. Serological analysis revealed that recombinant Phl p 11 shared epitopes for human IgE antibodies with the natural protein and bound serum IgE from 32% of grass pollen-sensitized subjects (n = 184). Purified recombinant Phl p 11 elicited skin reactions and dose-dependent histamine release from basophils of sensitized subjects, but not in non-allergic controls. CONCLUSION: As the first representative of group 11 grass pollen allergens, Phl p 11 has been cloned and produced as a recombinant protein showing allergenic activity. One-third of grass pollen-sensitized subjects showed specific IgE reactivity to recombinant Phl p 11, corresponding in magnitude to a significant proportion of specific IgE to grass pollen extract.

Amino Acid Sequence↗
PubMed2002

IgA autoreactivity: a feature common to inflammatory bowel and connective tissue diseases.

The immunopathogenic mechanisms in inflammatory bowel disease (IBD) are not yet fully established. The aim of this study was to determine the profile and magnitude of IgA and IgG autoantibodies in IBD patients. The autoantigen profile defined by IgA and IgG antibodies from 24 IBD (14 Crohn's disease CD], 10 ulcerative colitis UC]), three coeliac, 12 connective tissue disease (CTD) patients and 10 healthy individuals was studied in human cellular extracts by Western blotting. The magnitude of the IgA and IgG1-4 subclass responses was measured by ELISA. IBD patients could not be distinguished from healthy individuals on the basis of IgG autoantibodies to Western blotted proteins. IgG subclass analysis indicated no clear bias towards Th1 or Th2 immune responses in IBD or CTD. In accordance with previous work, we found that IgA autoreactivity was strongest in coeliac disease patients. Unexpectedly, IBD as well as CTD patients exhibited strong IgA autoantibody reactivities to components of similar molecular weights (16-80 kD) in intestinal and non-intestinal epithelial cell lines. Our data indicate immunopathogenic similarities between IBD and CTD.

Adult↗
PubMed2002

Nasal challenges with recombinant derivatives of the major birch pollen allergen Bet v 1 induce fewer symptoms and lower mediator release than rBet v 1 wild-type in patients with allergic rhinitis.

BACKGROUND: Genetic engineering of the major birch pollen allergen (Bet v 1) has led to the generation of recombinant Bet v 1 derivatives with markedly reduced IgE-binding capacity, but with retained T cell activating ability. OBJECTIVE: To compare the mucosal reactivity to rBet v 1 derivatives with rBet v 1 wild-type as basis for new therapeutic strategies for birch pollen allergy based on mucosal tolerance induction. METHODS: Outside the pollen season, 10 patients with birch pollen allergic rhinitis and mild asthma underwent four nasal challenge-sessions in a randomized, double-blind, and cross-over design, employing increasing doses of rBet v 1 fragment mix, rBet v 1 trimer, rBet v 1 wild-type and diluent (albumin). Nasal lavage fluids (NAL) were collected before the challenge-series as well as 10 min, 4 and 24 h thereafter. Nasal lavage fluid levels of tryptase as well as EPO and ECP were measured as indices of mast cell and eosinophil activity, respectively. RESULTS: All 10 patients tolerated the highest accumulated dose, 8.124 microg, when challenged with rBet v 1 trimer, eight with rBet v 1 fragments compared to one when challenged with rBet v 1 wild-type. No late phase reactions were observed. The change in tryptase levels (pre-challenge vs. 10 min) was significantly lower after challenges with rBet v 1 trimer and rBet v 1 fragments than with rBet v 1 wild-type. The change in EPO/ECP concentration pre-challenge versus 4 h post-challenge was lower for rBet v 1 trimer and the change was significantly lower when pre-challenge versus 24 h post-challenge to rBet v 1 fragments and rBet v 1 wild-type was examined. CONCLUSION: The derivatives induced significantly fewer symptoms and lower mast cell and eosinophil activation than rBet v 1 wild-type upon application to the nasal mucosa. They could in the future be candidates for immunotherapy based on mucosal tolerance induction.

Adult↗
PubMed2001

Molecular and immunological characterization of arginine kinase from the Indianmeal moth, Plodia interpunctella, a novel cross-reactive invertebrate pan-allergen.

IgE recognition of indoor allergens represents a major cause of allergic asthma in atopic individuals. We found that 52 of 102 patients suffering from allergic symptoms indoors contained IgE Abs against allergens from the Indianmeal moth (Plodia interpunctella), a ubiquitous food pest. Using serum IgE from a moth-sensitized patient we screened an expression cDNA library constructed from P. interpunctella larvae. cDNAs coding for arginine kinase (EC 2.7.3.3), a 40-kDa enzyme commonly occurring in invertebrates that is involved in the storage of such high-energy phosphate bonds as phosphoarginine, were isolated. Recombinant moth arginine kinase, designated Plo i 1, was expressed in Escherichia coli as a histidine-tagged protein with enzymatic activity, and purified to homogeneity by nickel chelate affinity chromatography. Purified recombinant arginine kinase induced specific basophil histamine release and immediate as well as late-phase skin reactions. It reacted with serum IgE from 13 of the 52 (25%) moth-allergic patients and inhibited the binding of allergic patients' IgE to an immunologically related 40-kDa allergen present in house dust mite, cockroach, king prawn, lobster, and mussel. Our results indicate that arginine kinases represent a new class of cross-reactive invertebrate pan-allergens. Recombinant arginine kinase may be used to identify a group of polysensitized indoor allergic patients and for immunotherapy of these individuals.

Adolescent↗
PubMed2001

Expression of mast cell tryptase by myeloblasts in a group of patients with acute myeloid leukemia.

alpha- and beta-tryptase genes encode serine proteases that are abundantly expressed by mast cells. Under physiologic conditions other myeloid cells are virtually tryptase negative. However, tryptases are also expressed in several myeloid leukemia cell lines. In this study, serum total tryptase levels were determined in 150 patients with acute leukemias (de novo acute myeloid leukemia [AML], n = 108; secondary AML, n = 25; acute lymphoid leukemia [ALL], n = 17) by fluoroenzyme immunoassay. In healthy subjects (n = 30), tryptase levels ranged between 2.0 and 12.6 ng/mL. Elevated tryptase levels (> 15) were detected in 42 (39%) of 108 patients with de novo AML and in 11 (44%) of 25 patients with secondary AML. No elevated tryptase levels were found in patients with ALL. In de novo AML, elevated tryptase levels were frequently detected in patients with French-American-British classification M0 (6 of 9), M2 (9 of 14), M3 (4 of 6), and M4eo (7 of 7), and less frequently in M1 (7 of 20), M4 (6 of 26), M5 (2 of 18), M6 (0 of 5), or M7 (1 of 3). The highest tryptase levels were found in M4eo. Immunohistochemical staining of bone marrow sections with anti-tryptase antibody as well as immunoelectron microscopy revealed tryptase expression in the cytoplasm of myeloblasts. As assessed by Northern blotting and reverse transcriptase-polymerase chain reaction, AML cells expressed alpha-tryptase messenger RNA (mRNA) but little or no beta-tryptase mRNA. In AML patients with elevated serum tryptase before chemotherapy, who entered complete remission, tryptase levels returned to normal or near normal values. Blast cell persistence or regrowth was associated with a persistently elevated level or recurrent increase of tryptase. Together, tryptase is expressed in myeloblasts in a group of AML and may serve as a useful disease-related marker.

Acute Disease↗
PubMed2001

Evaluation of the allergenic potential of Ginkgo biloba extracts.

Ginkgo biloba extracts are used for the treatment of central and peripheral malperfusion, cerebral insufficiency and dementia. Between 1996 and 1998, several patients in Austria who had received parenteral Ginkgo extracts were reported to have developed allergy-like symptoms. The aim of the present study was to determine whether Ginkgo biloba extracts contain type I allergens. The protein content of Ginkgo biloba extracts was determined by BCA protein determination and SDS-PAGE. We used sera from 95 polysensitized plant-allergic patients (the sera contained IgE antibodies against most plant allergens), and rabbit antisera raised against defined recombinant plant allergens. The presence of allergens in Ginkgo extracts was determined by dot-blotting and Wester blot. Neither rabbit antisera nor IgE antibodies of patients reacted to the Ginkgo extracts. In addition, it was shown that prick testing of the skin could be conveniently used to study Gingko extracts for allergenic activity. In conclusion, no evidence for the presence of type I allergens in Ginkgo extracts was found. We recommend serological and/or skin testing to exclude sensitisation to components of Ginkgo biloba extracts.

Adult↗
PubMed2001

Genetic engineering of a hypoallergenic trimer of the major birch pollen allergen Bet v 1.

An estimated 100 million individuals suffer from birch pollen allergy. Specific immunotherapy, the only curative allergy treatment, can cause life-threatening anaphylactic side effects. Here, we report the genetic engineering of a recombinant trimer consisting of three covalently linked copies of the major birch pollen allergen, Bet v 1. The trimer exhibited profoundly reduced allergenic activity but contained similar secondary structures such as Bet v 1 wild type, Bet v 1-specific B cell and T-cell epitopes, and induced Th1 cytokine release. As immunogen, rBet v 1 trimer induced IgG antibodies, which blocked patients' IgE binding to Bet v 1 and related allergens. Thus, rBet v 1 trimer represents a novel hypoallergenic vaccine prototype for treatment of one of the most frequent allergy forms.

Allergens↗
PubMed2001

Nonanaphylactic synthetic peptides derived from B cell epitopes of the major grass pollen allergen, Phl p 1, for allergy vaccination.

Worldwide more than 200 million individuals are allergic to group 1 grass pollen allergens. We have used the major timothy grass pollen allergen Phl p 1, which cross-reacts with most grass-, corn-, and monocot-derived group 1 allergens to develop a generally applicable strategy for the production of hypoallergenic allergy vaccines. On the basis of the experimentally determined B cell epitopes of Phl p 1, we have synthesized five synthetic peptides. These peptides are derived from the major Phl p 1 IgE epitopes and were between 28-32 amino acids long. We demonstrate by nuclear magnetic resonance that the peptides exhibit no secondary and tertiary structure and accordingly failed to bind IgE antibodies from grass pollen allergic patients. The five peptides, as well as an equimolar mixture thereof, lacked allergenic activity as demonstrated by basophil histamine release and skin test experiments in grass pollen allergic patients. When used as immunogens in mice and rabbits, the peptides induced protective IgG antibodies, which recognized the complete Phl p 1 wild-type allergen and group 1 allergens from other grass species. Moreover, peptide-induced antibodies inhibited the binding of grass pollen allergic patients IgE antibodies to the wild-type allergen. We thus demonstrate that synthetic hypoallergenic peptides derived from B cell epitopes of major allergens represent safe vaccine candidates for the treatment of IgE- mediated allergies.

Allergens↗
PubMed2001

IgA cross-reactivity between a nuclear autoantigen and wheat proteins suggests molecular mimicry as a possible pathomechanism in celiac disease.

Celiac disease patients display IgA antibody reactivity to wheat as well as to human proteins. We used serum IgA from celiac patients and, for control purposes, from patients with Crohn's disease, ulcerative colitis and from healthy individuals to identify celiac disease-specific IgA autoantigens in nitrocellulose-blotted extracts from various human cell types (epithelial, endothelial, intestinal cells, fibroblasts). The pattern, recognition intensity and time course of IgA autoreactivity was monitored using serial serum samples obtained from celiac children before and under gluten-free diet. By immunoblot inhibition and subcellular (cytosolic, nuclear) cell fractionation we identified a 55 kDa nuclear autoantigen expressed in intestinal, endothelial cells and in fibroblasts which was recognized by IgA antibodies of approximately half of the celiac disease patients and cross-reacted with wheat proteins. IgA reactivity to the 55 kDa autoantigen disappeared during gluten-free diet and was inhibited after pre-absorption of sera with wheat proteins but not with tissue transglutaminase, previously reported as the unique celiac disease-specific autoantigen. In conclusion, we defined a novel 55 kDa celiac disease-specific nuclear IgA autoantigen which shares epitopes with wheat proteins and which is different from tissue transglutaminase and calreticulin. Although the newly defined autoantigen was recognized much less frequently than tissue transglutaminase, our data suggest molecular mimicry between wheat and human proteins as a possible pathomechanism for the induction and/or maintenance of mucosal tissue damage in celiac disease.

Adolescent↗
PubMed2001

Identification of pronp1, a tobacco profilin gene activated in tip-growing cells.

In plant cells, several cellular processes depend on rapid reorganization of a dynamic network of actin cytoskeletal elements in response to internal and environmental stimuli. Profilins, ubiqitous eukaryotic actin monomer-binding proteins with highly conserved three-dimensional structures, regulate the actin cytoskeleton and are considered to link the microfilament system with signal transduction pathways. Plant profilins have been grouped into two distinct classes, gametophytic (pollen-specific) and sporophytic. Here we report the isolation of a profilin gene that seems to be activated during tip growth of specialized cells of gametophytic as well as sporophytic origin. Identification of a genomic DNA clone containing a tobacco profilin gene, pronp1, and analysis of the pronp1 promoter-uidA fusion gene in transgenic Nicotiana tabacum plants revealed a prominent expression of pronp1 in mature pollen and elongating pollen tubes and significant activity in root hairs of developing seedlings. This expression pattern was distinct from that of any other profilin gene isolated so far. Pronp1 thus represents a unique profilin gene that is activated at the transcriptional level in two kinds of tip-growing cells, pollen tubes and root hairs, both of which require rapid organization of the actin cytoskeleton. The isolation of such a gene has fundamental importance for our understanding of modulation of the actin cytoskeleton at the molecular level.

Contractile Proteins↗
PubMed2001

Recombinant allergen molecules: tools to study effector cell activation.

The IgE antibody-mediated activation of allergic effector cells is the key pathomechanism underlying the immediate symptoms of Type I allergy, a genetically determined hypersensitivity disease affecting 25% of the population. In recent years important environmental allergens and their epitopes have become available as structurally defined recombinant molecules. In addition, corresponding human monoclonal IgE and IgG antibodies have been isolated. This review summarizes data obtained regarding the three-dimensional structure of allergens, their IgE epitopes and the recognition of allergens by IgE and IgG antibodies. In particular, we discuss results of recent in vitro and in vivo studies with defined allergen molecules, their epitopes and the corresponding antibodies which support the hypothesis that the density and geometrical arrangement of IgE epitopes on a particular allergen molecule may profoundly affect effector cell activation. If the structural requirements for effector cell activation can be delineated, it may be envisaged that, based on this knowledge, allergens can be converted into hypoallergenic immunogens by reorientation of IgE epitopes. Such allergen derivatives may be used for allergen-specific immunotherapy with reduced risk of inducing anaphylactic side effects.

Allergens↗
PubMed2001

Skin test results but not serology reflect immediate type respiratory sensitivity: a study performed with recombinant allergen molecules.

The diagnosis of type I allergy, an IgE-antibody-mediated hypersensitivity disease affecting more than 25% of the population, is based on the measurement of allergen-specific serum IgE levels and provocation testing. Whether the determination of allergen- specific serum IgE levels can replace in vivo provocation testing for allergy diagnosis is a controversial issue. We used purified recombinant timothy grass and birch pollen allergens to compare by skin prick and nasal provocation testing as well as by serology in vivo sensitivity with antibody-binding capacity in 24 pollen allergic patients and eight control individuals. Results from biologic tests were correlated with each other and with allergen-specific IgE and IgG1-4 levels. IgE-reactive allergens induced immediate skin and nasal reactions, but the intensity of the allergic tissue reactions was not correlated with either the levels of allergen-specific IgE or the levels of allergen-specific IgG antibodies. Less frequently detected allergens with low IgE-binding capacity were able to induce strong allergic reactions comparable to those caused by major allergens with high IgE-binding capacity. In contrast, skin test and nasal provocation results were significantly correlated (r = 0.63, p < 0.01). Our study thus demonstrates on a molecular level that skin testing provides a better reflection of immediate type respiratory sensitivity than serologic measurements. These results have implications for allergy diagnosis and, in particular, for the selection of relevant allergen components for specific immunotherapy.

Allergens↗