Proteomic profiling of the weed feverfew, a neglected pollen allergen source.

Feverfew (Parthenium hysterophorus), an invasive weed from the Asteraceae family, has been reported as allergen source. Despite its relevance, knowledge of allergens is restricted to a partial sequence of a hydroxyproline-rich glycoprotein. We aimed to obtain the entire sequence for recombinant production and characterize feverfew pollen using proteomics and immunological assays. Par h 1, a defensin-proline fusion allergen was obtained by cDNA cloning and recombinantly produced in E. coli. Using two complementary proteomic strategies, a total of 258 proteins were identified in feverfew pollen among those 47 proteins belonging to allergenic families. Feverfew sensitized patients' sera from India revealed IgE reactivity with a pectate lyase, PR-1 protein and thioredoxin in immonoblot. In ELISA, recombinant Par h 1 was recognized by 60 and 40% of Austrian and Indian sera, respectively. Inhibition assays demonstrated the presence of IgE cross-reactive Par h 1, pectate lyase, lipid-transfer protein, profilin and polcalcin in feverfew pollen. This study reveals significant data on the allergenic composition of feverfew pollen and makes recombinant Par h 1 available for cross-reactivity studies. Feverfew might become a global player in weed pollen allergy and inclusion of standardized extracts in routine allergy diagnosis is suggested in exposed populations.

T Cell Epitope-Containing Domains of Ragweed Amb a 1 and Mugwort Art v 6 Modulate Immunologic Responses in Humans and Mice.

BACKGROUND: Ragweed (Ambrosia artemisiifolia) and mugwort (Artemisia vulgaris) are the major cause of pollen allergy in late summer. Allergen-specific lymphocytes are crucial for immune modulation during immunotherapy. We sought to generate and pre-clinically characterise highly immunogenic domains of the homologous pectate lyases in ragweed (Amb a 1) and mugwort pollen (Art v 6) for immunotherapy. METHODS: Domains of Amb a 1 (Amb a 1α) and Art v 6 (Art v 6α) and a hybrid molecule, consisting of both domains, were designed, expressed in E. coli and purified. Human IgE reactivity and allergenicity were assessed by ELISA and mediator release experiments using ragweed and mugwort allergic patients. Moreover, T cell proliferation was determined. Blocking IgG antibodies and cytokine production in BALB/c mice were studied by ELISA and ELISPOT. RESULTS: The IgE binding capacity and in vitro allergenic activity of the Amb a 1 and Art v 6 domains and the hybrid were either greatly reduced or abolished. The recombinant proteins induced T cell proliferative responses comparable to those of the natural allergens, indicative of retained allergen-specific T cell response. Mice immunisation with the hypoallergens induced IL-4, IL-5, IL-13 and IFN-γ production after antigen-specific in vitro re-stimulation of splenocytes. Moreover, murine IgG antibodies that inhibited specific IgE binding of ragweed and mugwort pollen allergic patients were detected. CONCLUSION: Accumulation of T cell epitopes and deletion of IgE reactive areas of Amb a 1 and Art v 6, modulated the immunologic properties of the allergen immuno-domains, leading to promising novel candidates for therapeutic approach.

Pectate lyase pollen allergens: sensitization profiles and cross-reactivity pattern.

BACKGROUND: Pollen released by allergenic members of the botanically unrelated families of Asteraceae and Cupressaceae represent potent elicitors of respiratory allergies in regions where these plants are present. As main allergen sources the Asteraceae species ragweed and mugwort, as well as the Cupressaceae species, cypress, mountain cedar, and Japanese cedar have been identified. The major allergens of all species belong to the pectate lyase enzyme family. Thus, we thought to investigate cross-reactivity pattern as well as sensitization capacities of pectate lyase pollen allergens in cohorts from distinct geographic regions. METHODS: The clinically relevant pectate lyase pollen allergens Amb a 1, Art v 6, Cup a 1, Jun a 1, and Cry j 1 were purified from aqueous pollen extracts, and patients' sensitization pattern of cohorts from Austria, Canada, Italy, and Japan were determined by IgE ELISA and cross-inhibition experiments. Moreover, we performed microarray experiments and established a mouse model of sensitization. RESULTS: In ELISA and ELISA inhibition experiments specific sensitization pattern were discovered for each geographic region, which reflected the natural allergen exposure of the patients. We found significant cross-reactivity within Asteraceae and Cupressaceae pectate lyase pollen allergens, which was however limited between the orders. Animal experiments showed that immunization with Asteraceae allergens mainly induced antibodies reactive within the order, the same was observed for the Cupressaceae allergens. Cross-reactivity between orders was minimal. Moreover, Amb a 1, Art v 6, and Cry j 1 showed in general higher immunogenicity. CONCLUSION: We could cluster pectate lyase allergens in four categories, Amb a 1, Art v 6, Cup a 1/Jun a 1, and Cry j 1, respectively, at which each category has the potential to sensitize predisposed individuals. The sensitization pattern of different cohorts correlated with pollen exposure, which should be considered for future allergy diagnosis and therapy.

Component-resolved IgE profiles in Austrian patients with a convincing history of peanut allergy.

BACKGROUND: Peanut allergy develops after primary sensitization to peanut allergens and/or IgE cross-sensitization with homologous allergens from various plants. Therefore, heterogeneous patterns of sensitization to individual peanut allergens are observed in different countries. The aim of this study was to examine the IgE sensitization patterns of Austrian peanut-allergic patients. METHODS: Sera from 65 peanut-allergic patients and 20 peanut-tolerant atopics were obtained in four Austrian allergy clinics. Sensitization patterns against peanut allergens Ara h 1-3, 6, 8 and 9 were identified by ImmunoCAP and ImmunoCAP ISAC. RESULTS: Austrian peanut-allergic patients were sensitized to Ara h 2 and 6 (71%), followed by Ara h 1 (62%), Ara h 8 (45%), Ara h 3 (35%) and Ara h 9 (11%). All sera containing Ara h 2-specific IgE were also positive for Ara h 6, with Ara h 6-specific IgE levels significantly (p < 0.05) higher compared with Ara h 2. Twelve percent displayed IgE reactivity exclusively to Ara h 8. Peanut extract and Ara h 8 showed low diagnostic specificities of 25 and 10%, respectively. The other peanut allergens showed 100% specificity. Diagnostic sensitivities determined by ImmunoCAP ISAC and ImmunoCAP were highly similar for Ara h 2, 3 and 8. CONCLUSIONS: The majority of symptomatic peanut-allergic patients are sensitized to Ara h 2 and Ara h 6. In peanut-symptomatic patients with additional birch pollen allergy, other peanut allergens, especially Ara h 8, should be tested when IgE reactivity to Ara h 2 is absent.

Guideline on allergen-specific immunotherapy in IgE-mediated allergic diseases: S2k Guideline of the German Society for Allergology and Clinical Immunology (DGAKI), the Society for Pediatric Allergy and Environmental Medicine (GPA), the Medical Association of German Allergologists (AeDA), the Austrian Society for Allergy and Immunology (ÖGAI), the Swiss Society for Allergy and Immunology (SGAI), the German Society of Dermatology (DDG), the German Society of Oto- Rhino-Laryngology, Head and Neck Surgery (DGHNO-KHC), the German Society of Pediatrics and Adolescent Medicine (DGKJ), the Society for Pediatric Pneumology (GPP), the German Respiratory Society (DGP), the German Association of ENT Surgeons (BV-HNO), the Professional Federation of Paediatricians and Youth Doctors (BVKJ), the Federal Association of Pulmonologists (BDP) and the German Dermatologists Association (BVDD).

The present guideline (S2k) on allergen-specific immunotherapy (AIT) was established by the German, Austrian and Swiss professional associations for allergy in consensus with the scientific specialist societies and professional associations in the fields of otolaryngology, dermatology and venereology, pediatric and adolescent medicine, pneumology as well as a German patient organization (German Allergy and Asthma Association; Deutscher Allergie- und Asthmabund, DAAB) according to the criteria of the Association of the Scientific Medical Societies in Germany (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften, AWMF). AIT is a therapy with disease-modifying effects. By administering allergen extracts, specific blocking antibodies, toler-ance-inducing cells and mediators are activated. These prevent further exacerbation of the allergen-triggered immune response, block the specific immune response and attenuate the inflammatory response in tissue. Products for SCIT or SLIT cannot be compared at present due to their heterogeneous composition, nor can allergen concentrations given by different manufacturers be compared meaningfully due to the varying methods used to measure their active ingredients. Non-modified allergens are used for SCIT in the form of aqueous or physically adsorbed (depot) extracts, as well as chemically modified allergens (allergoids) as depot extracts. Allergen extracts for SLIT are used in the form of aqueous solutions or tablets. The clinical efficacy of AIT is measured using various scores as primary and secondary study endpoints. The EMA stipulates combined symptom and medication scores as primary endpoint. A harmonization of clinical endpoints, e. g., by using the combined symptom and medication scores (CSMS) recommended by the EAACI, is desirable in the future in order to permit the comparison of results from different studies. The current CONSORT recommendations from the ARIA/GA2LEN group specify standards for the evaluation, presentation and publication of study results. According to the Therapy allergen ordinance (TAV), preparations containing common allergen sources (pollen from grasses, birch, alder, hazel, house dust mites, as well as bee and wasp venom) need a marketing authorization in Germany. During the marketing authorization process, these preparations are examined regarding quality, safety and efficacy. In the opinion of the authors, authorized allergen preparations with documented efficacy and safety, or preparations tradeable under the TAV for which efficacy and safety have already been documented in clinical trials meeting WAO or EMA standards, should be preferentially used. Individual formulations (NPP) enable the prescription of rare allergen sources (e.g., pollen from ash, mugwort or ambrosia, mold Alternaria, animal allergens) for specific immunotherapy. Mixing these allergens with TAV allergens is not permitted. Allergic rhinitis and its associated co-morbidities (e. g., bronchial asthma) generate substantial direct and indirect costs. Treatment options, in particular AIT, are therefore evaluated using cost-benefit and cost-effectiveness analyses. From a long-term perspective, AIT is considered to be significantly more cost effective in allergic rhinitis and allergic asthma than pharmacotherapy, but is heavily dependent on patient compliance. Meta-analyses provide unequivocal evidence of the efficacy of SCIT and SLIT for certain allergen sources and age groups. Data from controlled studies differ in terms of scope, quality and dosing regimens and require product-specific evaluation. Therefore, evaluating individual preparations according to clearly defined criteria is recommended. A broad transfer of the efficacy of certain preparations to all preparations administered in the same way is not endorsed. The website of the German Society for Allergology and Clinical Immunology (www.dgaki.de/leitlinien/s2k-leitlinie-sit; DGAKI: Deutsche Gesellschaft für Allergologie und klinische Immunologie) provides tables with specific information on available products for AIT in Germany, Switzerland and Austria. The tables contain the number of clinical studies per product in adults and children, the year of market authorization, underlying scoring systems, number of randomized and analyzed subjects and the method of evaluation (ITT, FAS, PP), separately given for grass pollen, birch pollen and house dust mite allergens, and the status of approval for the conduct of clinical studies with these products. Strong evidence of the efficacy of SCIT in pollen allergy-induced allergic rhinoconjunctivitis in adulthood is well-documented in numerous trials and, in childhood and adolescence, in a few trials. Efficacy in house dust mite allergy is documented by a number of controlled trials in adults and few controlled trials in children. Only a few controlled trials, independent of age, are available for mold allergy (in particular Alternaria). With regard to animal dander allergies (primarily to cat allergens), only small studies, some with methodological deficiencies are available. Only a moderate and inconsistent therapeutic effect in atopic dermatitis has been observed in the quite heterogeneous studies conducted to date. SCIT has been well investigated for individual preparations in controlled bronchial asthma as defined by the Global Initiative for Asthma (GINA) 2007 and intermittent and mild persistent asthma (GINA 2005) and it is recommended as a treatment option, in addition to allergen avoidance and pharmacotherapy, provided there is a clear causal link between respiratory symptoms and the relevant allergen. The efficacy of SLIT in grass pollen-induced allergic rhinoconjunctivitis is extensively documented in adults and children, whilst its efficacy in tree pollen allergy has only been shown in adults. New controlled trials (some with high patient numbers) on house dust mite allergy provide evidence of efficacy of SLIT in adults. Compared with allergic rhinoconjunctivitis, there are only few studies on the efficacy of SLIT in allergic asthma. In this context, newer studies show an efficacy for SLIT on asthma symptoms in the subgroup of grass pollen allergic children, adolescents and adults with asthma and efficacy in primary house dust mite allergy-induced asthma in adolescents aged from 14 years and in adults. Aspects of secondary prevention, in particular the reduction of new sensitizations and reduced asthma risk, are important rationales for choosing to initiate treatment early in childhood and adolescence. In this context, those products for which the appropriate effects have been demonstrated should be considered. SCIT or SLIT with pollen or mite allergens can be performed in patients with allergic rhinoconjunctivitis using allergen extracts that have been proven to be effective in at least one double-blind placebo-controlled (DBPC) study. At present, clinical trials are underway for the indication in asthma due to house dust mite allergy, some of the results of which have already been published, whilst others are still awaited (see the DGAKI table "Approved/potentially completed studies" via www.dgaki.de/Leitlinien/s2k-Leitlinie-sit (according to www.clinicaltrialsregister.eu)). When establishing the indication for AIT, factors that favour clinical efficacy should be taken into consideration. Differences between SCIT and SLIT are to be considered primarily in terms of contraindications. In individual cases, AIT may be justifiably indicated despite the presence of contraindications. SCIT injections and the initiation of SLIT are performed by a physician experienced in this type of treatment and who is able to administer emergency treatment in the case of an allergic reaction. Patients must be fully informed about the procedure and risks of possible adverse events, and the details of this process must be documented (see "Treatment information sheet"; available as a handout via www.dgaki.de/Leitlinien/s2k-Leitlinie-sit). Treatment should be performed according to the manufacturer's product information leaflet. In cases where AIT is to be performed or continued by a different physician to the one who established the indication, close cooperation is required in order to ensure that treatment is implemented consistently and at low risk. In general, it is recommended that SCIT and SLIT should only be performed using preparations for which adequate proof of efficacy is available from clinical trials. Treatment adherence among AIT patients is lower than assumed by physicians, irrespective of the form of administration. Clearly, adherence is of vital importance for treatment success. Improving AIT adherence is one of the most important future goals, in order to ensure efficacy of the therapy. Severe, potentially life-threatening systemic reactions during SCIT are possible, but - providing all safety measures are adhered to - these events are very rare. Most adverse events are mild to moderate and can be treated well. Dose-dependent adverse local reactions occur frequently in the mouth and throat in SLIT. Systemic reactions have been described in SLIT, but are seen far less often than with SCIT. In terms of anaphylaxis and other severe systemic reactions, SLIT has a better safety profile than SCIT. The risk and effects of adverse systemic reactions in the setting of AIT can be effectively reduced by training of personnel, adhering to safety standards and prompt use of emergency measures, including early administration of i. m. epinephrine. Details on the acute management of anaphylactic reactions can be found in the current S2 guideline on anaphylaxis issued by the AWMF (S2-AWMF-LL Registry Number 061-025). AIT is undergoing some innovative developments in many areas (e. g., allergen characterization, new administration routes, adjuvants, faster and safer dose escalation protocols), some of which are already beinginvestigated in clinical trials. Cite this as Pfaar O, Bachert C, Bufe A, Buhl R, Ebner C, Eng P, Friedrichs F, Fuchs T, Hamelmann E, Hartwig-Bade D, Hering T, Huttegger I, Jung K, Klimek L, Kopp MV, Merk H, Rabe U, Saloga J, Schmid-Grendelmeier P, Schuster A, Schwerk N, Sitter H, Umpfenbach U, Wedi B, Wöhrl S, Worm M, Kleine-Tebbe J. Guideline on allergen-specific immunotherapy in IgE-mediated allergic diseases - S2k Guideline of the German Society for Allergology and Clinical Immunology (DGAKI), the Society for Pediatric Allergy and Environmental Medicine (GPA), the Medical Association of German Allergologists (AeDA), the Austrian Society for Allergy and Immunology (ÖGAI), the Swiss Society for Allergy and Immunology (SGAI), the German Society of Dermatology (DDG), the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery (DGHNO-KHC), the German Society of Pediatrics and Adolescent Medicine (DGKJ), the Society for Pediatric Pneumology (GPP), the German Respiratory Society (DGP), the German Association of ENT Surgeons (BV-HNO), the Professional Federation of Paediatricians and Youth Doctors (BVKJ), the Federal Association of Pulmonologists (BDP) and the German Dermatologists Association (BVDD). Allergo J Int 2014;23:282-319.

Oral exposure to Mal d 1 affects the immune response in patients with birch pollen allergy.

BACKGROUND: Antibodies and T cells specific for the major birch pollen allergen Bet v 1 cross-react with structurally related food allergens, such as Mal d 1 in apple. OBJECTIVE: We sought to evaluate the effects of oral uptake of Mal d 1 on the allergen-specific immune response in patients with birch pollen allergy. METHODS: Patients received 50 µg of rBet v 1 sublingually on 2 consecutive days outside of the birch pollen season. One year later, equal amounts of rMal d 1 were administered. Blood samples were collected before and after oral exposure, as well as before and after the intermediate birch pollen season. Allergen-specific IgE levels were determined by using ImmunoCAP. Proliferation of allergen-stimulated PBMCs was assessed, as well as the expression of IL-5, IL-13, IL-10, IFN-γ, and forkhead box protein 3 (Foxp3) in isolated T cells (real-time PCR). Allergen-specific T-cell lines were analyzed for epitope recognition. RESULTS: Orally administered Bet v 1 transiently reduced Bet v 1-specific serum IgE levels, as well as Bet v 1- and Mal d 1-induced T-cell proliferation, and enhanced the expression of IL-5, IL-10, and Foxp3. Orally applied Mal d 1 significantly decreased Bet v 1- and Mal d 1-specific IgE levels and induced IL-5 and IL-10 but no Foxp3 expression. In contrast to Bet v 1, Mal d 1 triggered IFN-γ production and T cells with a different epitope repertoire. Inhalation of birch pollen significantly enhanced allergen-specific IgE levels, T-cell proliferation, and IL-5, IL-10, IL-13, and Foxp3 expression. CONCLUSION: Two sublingual administrations of 50 µg of Mal d 1 were well tolerated and induced transient immune responses seen during peripheral tolerance development. Thus recombinant Mal d 1 might be suitable and relevant for sublingual treatment of birch pollen-related apple allergy.

Association of HLA-DR1 with the allergic response to the major mugwort pollen allergen: molecular background.

BACKGROUND: Mugwort pollen allergens represent the main cause of pollinosis in late summer. The major allergen, Art v 1, contains only one single immunodominant, solely HLA-DR-restricted T cell epitope (Art v 125-36). The frequency of HLA-DRB1*01 is highly increased in mugwort-allergic individuals and HLA-DR1 serves as restriction element for Art v 125-36. However, Art v 125-36 also binds to HLA-DR4 with high affinity and DR1-restricted Art v 125-36 -specific T cell receptors can be activated by HLA-DR4 molecules. To understand the predominance of HLA-DR1 in mugwort allergy in spite of the degeneracy in HLA/peptide-binding and TCR-recognition, we investigated the molecular background of Art v 125-36 /MHC/TCR interactions in the context of HLA-DR1 compared to -DR4. RESULTS: The majority of Art v 125-36 -specific T cell lines and clones from HLA-DR1 carrying, mugwort pollen-allergic donors reacted to synthetic and naturally processed Art v 1-peptides when presented by HLA-DR1 or HLA-DR4 expressing antigen presenting cells. However, at limiting peptide concentrations DR1 was more effective in T cell stimulation. In addition, the minimal epitope for 50% of Art v 125-36 -specific T cells was shorter for DR1 than for DR4. In vitro binding assays of Art v 125-36 mutant peptides to isolated DR1- and DR4-molecules indicated similar binding capacities and use of the same register. In silico simulation of Art v 125-36 binding to HLA-DR1 and -DR4 suggested similar binding of the central part of the peptide to either molecule, but a higher flexibility of the N- and C-terminal amino acids and detachment at the C-terminus in HLA-DR1. CONCLUSIONS: The predominance of HLA-DR1 in the response to Art v 125-36 may be explained by subtle conformation changes of the peptide bound to DR1 compared to DR4. Computer simulation supported our experimental data by demonstrating differences in peptide mobility within the HLA-DR complex that may influence TCR-binding. We suggest that the minor differences observed in vitro may be more relevant in the microenvironment in vivo, so that only presentation by HLA-DR1, but not -DR4 permits successful T cell activation.

Humoral and cellular cross-reactivity between Amb a 1, the major ragweed pollen allergen, and its mugwort homolog Art v 6.

Ragweed and mugwort are closely related weeds that represent the major cause of pollen allergy in late summer. Concomitant sensitization and clinical cross-reactivity frequently occur in subjects who are coexposed to both pollen species, and have implications for diagnosis and specific immunotherapy. Molecules involved in this cross-reactivity might be Amb a 1, the major ragweed pollen allergen, and Art v 6, a highly homologous allergen from mugwort. Therefore, we investigated the IgE and T cell response to Art v 6 of 60 weed pollen-allergic patients and assessed its immunological cross-reactivity with Amb a 1. Results of ELISA inhibition experiments suggested that both allergens are largely cross-reactive, but Amb a 1 possesses more IgE epitopes than Art v 6. In patients with IgE to both allergens, Amb a 1-induced T cell lines and clones responded weakly to Art v 6. Moreover, Art v 6-induced T cell lines responded stronger to Amb a 1. T cell epitope mapping of Art v 6 revealed that it contains only a few cross-reactive epitopes, which is opposed to the multiple T cell-activating regions present in Amb a 1. In summary, Amb a 1 can elicit more diverse allergen-specific IgE and T cell responses than Art v 6 and dominates the cross-reactivity with its homolog. Nevertheless, Art v 6 can act as a primary sensitizing allergen in areas with high mugwort pollen exposure, and consequently may facilitate sensitization to Amb a 1 by epitope cross-recognition of T and B cells.

Birch pollen-related food allergy: clinical aspects and the role of allergen-specific IgE and IgG4 antibodies.

BACKGROUND: Patients with birch pollen allergy often develop allergic reactions to plant foods. OBJECTIVE: To evaluate the prevalence, main symptoms, and triggers of birch pollen-related food allergy and the role of food-specific IgG(4) antibodies in food tolerance. METHODS: Food-induced symptoms were evaluated in 225 individuals with birch pollen allergy by using a standardized questionnaire. IgE and IgG(4) levels specific for the major birch pollen allergen Bet v 1 and birch profilin Bet v 2 and the Bet v 1 homologs in apple (Mal d 1) and hazelnut (Cor a 1) were quantified by ImmunoCAP. Mock-treated and IgG-depleted sera from patients tolerating hazelnuts in food challenges were compared for their inhibitory activity for binding of Cor a 1-IgE complexes to B cells. RESULTS: In total, 73% of the study population experienced food allergy, which was perennial in 86% of the affected individuals. The oral allergy syndrome was the main clinical manifestation. However, more than 58% of the patients also experienced food-induced rhinoconjunctivitis. Apples and hazelnuts were identified as the most frequent triggers. Food allergy correlated with IgE reactivity to Bet v 1 but not to Bet v 2. Mal d 1-specific and Cor a 1-specific IgG(4)/IgE ratios were significantly higher in food-tolerant individuals than individuals with food allergy. Sera from IgG(4)-positive food-tolerant patients possessed IgG-dependent IgE-inhibitory activity. CONCLUSION: Birch pollen-related food allergy is highly prevalent and often perennial. High food allergen-specific IgG(4)/IgE ratios seem associated with food tolerance, potentially because specific IgG(4) blocks IgE binding to food allergens. Thus, the presence of food allergen-specific IgG(4) antibodies is no diagnostic marker for birch pollen-related food allergy.

Targeting the cysteine-stabilized fold of Art v 1 for immunotherapy of Artemisia pollen allergy.

Plants of the genus Artemisia domestic in Northern and Central Europe, USA and parts of Asia are a major cause of allergic symptoms from late summer to autumn. Art v 1, the major mugwort pollen allergen appears as two-domain glycoprotein, consisting of an N-terminal defensin-like and a proline/hydroxyproline-rich C-terminal part. Patients sensitized to Art v 1 commonly display IgE antibodies against the cysteine-stabilized defensin fold. Site-directed mutagenesis of eight cysteines was used to disrupt disulfide bonds to generate molecules with altered IgE-binding capacity. Engineered constructs were expressed in E. coli and recombinant proteins were tested for their allergenic and T cell reactivity as well as for their physicochemical characteristics. Three cysteine variants (C22S, C47S, and C49S) exhibited extremely low IgE-binding activity in immunoblot and ELISA using sera from Art v 1-allergic patients. Mediator release assays using rat basophil leukemia cells showed that these variants displayed a 1x10(5)-fold reduced allergenic potency as compared to wild-type protein. All variants were able to activate allergen-specific T cells in PBMC, as well as Art v 1-specific T cell lines and clones. Variant C49S displayed an increased hydrophobic surface potential which correlated with an advanced activation of allergen-specific T cells. The low allergenicity and high immunogenic activity of Art v 1 variant C49S renders the molecule an attractive candidate for hypoallergen-based immunotherapy of Artemisia pollen allergy.

The influence of recombinant production on the immunologic behavior of birch pollen isoallergens.

BACKGROUND: Allergic reactions towards the birch major pollen allergen Bet v 1 are among the most common causes of spring pollinosis in the temperate climate zone of the Northern hemisphere. Natural Bet v 1 is composed of a complex mixture of different isoforms. Detailed analysis of recombinant Bet v 1 isoforms revealed striking differences in immunologic as well as allergenic properties of the molecules, leading to a classification of Bet v 1 isoforms into high, medium, and low IgE binding proteins. Especially low IgE binding Bet v 1 isoforms have been described as ideal candidates for desensitizing allergic patients with allergen specific immunotherapy (SIT). Since diagnosis and therapy of allergic diseases are highly dependent on recombinant proteins, continuous improvement of protein production is an absolute necessity. METHODOLOGY: Therefore, two different methods for recombinant production of a low IgE binding Bet v 1 isoform were applied; one based on published protocols, the other by implementing latest innovations in protein production. Both batches of Bet v 1.0401 were extensively characterized by an array of physicochemical as well as immunological methods to compare protein primary structure, purity, quantity, folding, aggregation state, thermal stability, and antibody binding capacity. CONCLUSION: The experiments demonstrated that IgE antibody binding properties of recombinant isoallergens can be significantly influenced by the production method directly affecting possible clinical applications of the molecules.

Role of the polypeptide backbone and post-translational modifications in cross-reactivity of Art v 1, the major mugwort pollen allergen.

Artemisia vulgaris (mugwort) is one of the main causes of late summer pollinosis in Europe, with >95% of patients sensitized to the glycoallergen Art v 1. Despite the importance of this allergen, little is known about its cross-reactive behavior. Here we investigated the occurrence of conserved Art v 1 antigenic determinants in sources known to display clinically relevant cross-reactivity with mugwort pollen. For this purpose, monoclonal antibodies specific for a cysteine-stabilized epitope of the Art v 1 defensin domain and for carbohydrates attached to the proline domain were produced by hybridoma and phage display technologies. Using polyclonal Art v 1-specific rabbit sera and antibodies against both the Art v 1 carbohydrate and polypeptide moieties, we could identify cross-reactive structures in pollen from botanically related Asteraceae weeds (Artemisia absinthium, Helianthus annuus and Ambrosia sp.). Homologous allergens were also recognized by IgE from mugwort-sensitized patients and the reactivity could be decreased by serum pre-incubation with natural and recombinant Art v 1. As no cross-reactive structures could be found in foods associated with mugwort pollinosis, we conclude that Art v 1 is poorly involved in mugwort cross-reactivity to food allergens.

The alpha and beta subchain of Amb a 1, the major ragweed-pollen allergen show divergent reactivity at the IgE and T-cell level.

Ragweed is one of the most important pollen allergens in North America and parts of Europe. Although the major allergen Amb a 1 was isolated and cloned in 1991, recombinant Amb a 1 was not explored further to improve diagnosis and specific immunotherapy of ragweed-pollen allergy. In the present study the immunological properties of natural Amb a 1 and its proteolytical cleavage products was investigated in detail and compared with recombinant produced Amb a 1 variants. Characterization of natural Amb a 1 and the identification of its proteolytic fragments, designated Amb a 1 alpha and Amb a 1 beta, was performed by N-terminal sequencing and mass spectroscopy. Amb a 1 and fragments were further produced in Escherichia coli, purified, and immunologically characterized. Amb a 1-specific T-cell cultures were used to compare the T-cell response to the different Amb a 1 variants. Divergent immunological properties of Amb a 1 alpha (aa 181-396) and Amb a 1 beta (aa 26-180) were revealed. Amb a 1 beta contained important IgE epitopes, whereas Amb a 1 alpha showed low IgE binding. When compared to natural Amb a 1, all recombinant variants possessed >100-fold reduced IgE-mediated mediator release activity. At the T-cell level recombinant and natural Amb a 1 stimulated comparable T-cell responses and the T-cell reactivity was largely directed to the C-terminal part. The results demonstrated that recombinant Amb a 1 alpha behaves as hypoallergen with reduced IgE binding but preservation of the major T-cell reactivity. In addition, recombinant Amb a 1 alpha can be easily purified to homogeneity in large quantity and therefore represents an ideal candidate for specific immunotherapy.

Immune recognition of novel isoforms and domains of the mugwort pollen major allergen Art v 1.

Allergen isoforms can differ in their IgE and T cell recognition patterns, and thus might have an impact on the selection of candidates for molecule-based diagnostic and therapeutic approaches. The present study aimed at the identification and characterization of isoforms of Art v 1, the mugwort pollen major allergen. In addition, single Art v 1 domains were physicochemically and immunologically characterized. For this purpose, the Art v 1 cDNA was radiolabeled and used to screen a mugwort pollen cDNA library. Positive clones were sequenced and used for the production of recombinant proteins in Escherichia coli using the pHIS-Parallel2 vector. Protein purification was performed by affinity- and ion exchange chromatography. Antibody binding to the recombinant proteins was determined by immunoblot, ELISA, cross-inhibition experiments, and mediator release assays. We could identify 7 Art v 1 isoforms differing in 1-6 amino acid residues. Interestingly, all amino acid variations were restricted to the proline domain carrying the molecule's post-translational modifications. No significant difference in IgG or IgE reactivity could be observed between Art v 1 isoforms and the defensin domain produced in E. coli. When expressed in E. coli, the proline domain was not recognized by Art v 1-specific antibodies. Our results demonstrated that the relevant IgE epitopes of Art v 1 are located on the defensin domain and suggest the involvement of carbohydrates in the allergenicity of natural Art v 1. Plant-based expression systems could help to reveal possibly different glycosylation patterns and IgE binding properties of Art v 1 isoforms. These findings have direct implications on the development of novel tools for mugwort pollen allergy diagnosis and therapy.

Characterization of HLA class II/peptide-TCR interactions of the immunodominant T cell epitope in Art v 1, the major mugwort pollen allergen.

More than 95% of mugwort pollen-allergic individuals are sensitized to Art v 1, the major allergen in mugwort pollen. Interestingly, the CD4 T cell response to Art v 1 involves only one single immunodominant peptide, Art v 1(25-36) (KCIEWEKAQHGA), and is highly associated with the expression of HLA-DR1. Therefore, we investigated the molecular basis of this unusual immunodominance among allergens. Using artificial APC expressing exclusively HLA-DRB1*0101 and HLA-DRA*0101, we formally showed that DR1 acts as restriction element for Art v 1(25-36)-specific T cell responses. Further assessment of binding of Art v 1(25-36) to artificial HLA-DR molecules revealed that its affinity was high for HLA-DR1. Amino acid I27 was identified as anchor residue interacting with DR molecules in pocket P1. Additionally, Art v 1(25-36) bound with high affinity to HLA-DRB1*0301 and *0401, moderately to HLA-DRB1*1301 and HLA-DRB5*0101, and weakly to HLA-DRB1*1101 and *1501. T cell activation was also inducible by Art v 1(25-36)-loaded, APC-expressing HLA molecules other than DR1, indicating degeneracy of peptide binding and promiscuity of TCR recognition. Specific binding of HLA-DRB1*0101 tetramers containing Art v 1(19-36) allowed the identification of Art v 1(25-36)-specific T cells by flow cytometry. In summary, the immunodominance of Art v 1(25-36) relies on its affinity to DR1, but is not dictated by it. Future investigations at the molecular HLA/peptide/TCR and cellular level using mugwort pollen allergy as a disease model may allow new insights into tolerance and pathomechanisms operative in type I allergy, which may instigate new, T cell-directed strategies in specific immunotherapy.

Sublingual immunotherapy induces IL-10-producing T regulatory cells, allergen-specific T-cell tolerance, and immune deviation.

BACKGROUND: The immunologic mechanisms underlying sublingual immunotherapy (SLIT) are still unclear, particularly the role of regulatory T cells. OBJECTIVE: We sought to characterize allergen-specific T-cell responses during successful birch pollen SLIT. METHODS: Proliferation of PBMCs and PBMCs depleted of CD25(+) cells obtained from 9 patients before, after 4 weeks, and after 52 weeks of SLIT was assessed in response to the major birch pollen allergen Bet v 1, the homologous apple allergen Mal d 1, or tetanus toxoid. Allergen-induced cytokine responses and FoxP3 expression of T cells were analyzed by using real-time PCR. The role of IL-10 for regulatory activity of T cells was investigated. RESULTS: After 4 weeks, higher frequencies of circulating CD4(+)CD25(+) T cells were detected together with increased FoxP3 and IL-10 and reduced IL-4 and IFN-gamma mRNA expression levels compared with those before SLIT. Proliferation to all 3 antigens was markedly reduced but increased significantly after depletion of CD25(+) cells or addition of anti-IL-10 antibodies. After 52 weeks, proliferation in response to Mal d 1 or tetanus toxoid returned to pre-SLIT levels, whereas Bet v 1-induced proliferation remained significantly suppressed and was enhanced by neither depletion of CD25(+) cells nor addition of anti-IL-10 antibodies. In parallel, increased IFN-gamma and reduced IL-4, IL-10, and FoxP3 mRNA expression was detected. Neither TGF-beta levels nor cell-cell contact-mediated suppression of CD4(+)CD25(+) cells changed during the course of SLIT. CONCLUSION: SLIT induces regulatory T-cell suppression through IL-10 during the early phase and specific nonreactivity and immune deviation of allergen-specific T cells during the later phase of therapy. CLINICAL IMPLICATIONS: SLIT induces immune mechanisms comparable with subcutaneous specific immunotherapy.

Allergy multivaccines created by DNA shuffling of tree pollen allergens.

BACKGROUND: The major allergens of trees belonging to the Fagales order are collectively known as the Bet v 1 family. Members of the Fagales order have distinct geographic distribution, and it is expected that depending on the exposure pattern of the individual, inclusion of other Bet v 1 family members might increase the efficacy of the treatment. OBJECTIVE: We aimed to generate molecules that are suitable for specific immunotherapy not only against birch pollen allergy but also against allergies caused by other cross-reactive tree pollens. METHODS: Fourteen genes of the Bet v 1 family were randomly recombined in vitro by means of DNA shuffling. This library of chimeric proteins was screened for molecules displaying low capacity to induce release of inflammatory mediators but with T-cell immunogenicity higher than that of the parental allergens. RESULTS: Two chimeric proteins were selected from the library of shuffled clones displaying low allergenicity and high immunogenicity, as determined in in vitro assays using human and animal cells and antibodies, as well as in vivo in animal models of allergy. CONCLUSION: Our results show that it is possible to randomly recombine in vitro T- and B-cell epitopes of a family of related allergens and to select chimeric proteins that perfectly match the criteria presently thought to be relevant for improving allergen-specific immunotherapy. CLINICAL IMPLICATIONS: The hypoallergenic chimeras described here recombine epitopes of the major Fagales pollen allergens and thus can efficiently substitute a mixture of extracts used for treating patients with tree pollen-induced spring pollinosis worldwide.