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Background: Non‐sedating H1‐antihistamines (nsAH) are the most commonly used treatment for chronic spontaneous urticaria (CSU). Many patients use them as on‐demand (OD) therapy rather than a maintenance treatment. Here, we compared OD versus daily maintenance treatment with the nsAH rupatadine, assessed the efficacy of rupatadine updosing, and investigated potential long‐term disease‐modifying effects. Methods: This multicenter, randomized study consisted of 2 weeks of screening, 8 weeks of double‐blind treatment, and 6 weeks of treatment‐free follow‐up (OD allowed). Adult patients were randomized to 10 mg rupatadine OD or 10 mg rupatadine daily. At Week 4, if patients did not have a complete response, they switched from 10 to 20 mg rupatadine daily or underwent sham updosing (patients on 10 mg rupatadine OD). The primary aim was to compare CSU disease activity at the end of follow‐up between daily versus OD. Additionally, we assessed the efficacy of rupatadine updosing. Major outcomes were disease activity, CSU‐related quality of life (QoL), and disease control. Results: At Week 4, disease activity and QoL significantly improved in daily versus OD‐treated patients. Updosing of rupatadine did not improve the mean disease activity, but the number of complete responders increased during updosing from 5% to 22%. At the end of follow‐up, the disease activity of patients treated OD versus daily was not significantly different. Conclusions: Daily rupatadine treatment significantly improved CSU disease activity and QoL during treatment versus OD treatment but not after discontinuation of rupatadine, indicating the benefits of a daily maintenance nsAH schedule. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: The consensus‐based guideline "Diagnosis, prevention, and treatment of hand eczema (HE)" provides concrete instructions and recommendations for diagnosis, prevention, and therapy of HE based on an evidence‐ and consensus‐based approach. The guideline was created based on the German guideline "Management von Handekzemen" from 2009 and the current guideline of the European Society of Contact Dermatitis (ESCD) "Guidelines for diagnosis, prevention, and treatment of hand eczema" from 2022. The general goal of the guideline is to provide dermatologists and allergologists in practice and clinics with an accepted, evidence‐based decision‐making tool for selecting and conducting suitable and sufficient therapy for patients with hand eczema. The guideline is based on two Cochrane reviews of therapeutic and preventive interventions for HE. The remaining chapters were mainly developed and consented based on non‐systematic literature research by the expert group. The expert group consisted of members of allergological and occupational dermatological professional associations and working groups, a patient representative, and methodologists. The proposals for recommendations and key statements were consented by using a nominal group process during a consensus conference on September 15, 2022. The structured consensus‐building process was professionally moderated. This guideline is valid until February 22, 2028. [ABSTRACT FROM AUTHOR]

Summary: This publication is the second part of the German‐language S3 guideline on urticaria. It covers the management of urticaria and should be used together with Part 1 of the guideline on classification and diagnosis. This publication was prepared according to the criteria of the AWMF on the basis of the international English‐language S3 guideline with special consideration of health system conditions in German‐speaking countries. Chronic urticaria has a high impact on the quality of life and daily activities of patients. Therefore, if causal factors cannot be eliminated, effective symptomatic treatment is necessary. The recommended first‐line treatment is to administer new generation, non‐sedating H1 antihistamines. If the standard dose is not sufficiently effective, the dose should be increased up to fourfold. For patients who do not respond to this treatment, the second‐line treatment in addition to antihistamines in the treatment algorithm is omalizumab and, if this treatment fails, ciclosporin. Other low‐evidence therapeutic agents should only be used if all treatments in the treatment algorithm agreed upon by the guideline group fail. Both the benefit‐risk profile and cost should be considered. Corticosteroids are not recommended for long‐term treatment due to their inevitable severe side effects. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: The lifetime prevalence of urticaria, a severe allergic disease, is almost 20%. It not only limits the quality of life of those affected, but also their general performance at work and in their daily activities. This publication is the first section of the Urticaria Guideline. It covers the classification and diagnosis of urticaria, taking into account the major advances in research into its causes, triggering factors and pathomechanisms. It also addresses strategies for the efficient diagnosis of the different subtypes of urticaria. This is crucial for individual, patient‐oriented treatment, which is covered in the second part of the guideline, published separately. This German‐language guideline was developed according to the criteria of the AWMF on the basis of the international English‐language S3 guideline with special consideration of health system characteristics in the German‐speaking countries. This first part of the guideline describes the classification of urticaria, distinguishing spontaneously occurring wheals (hives) and angioedema from forms of urticaria with inducible symptoms. Urticaria is defined as sudden onset of wheals, angioedema, or both, but is to be distinguished from conditions in which wheals occur as a short‐term symptom, such as anaphylaxis. The diagnosis is based on (a limited number of) laboratory tests, but especially on medical history. In addition, validated instruments are available to measure the severity, activity and course of the disease. [ABSTRACT FROM AUTHOR]

Background: Systemic allergic reactions to vaccines are very rare. In this study we assessed the management and outcome of suspected SARS‐CoV‐2 vaccine hypersensitivity. Methods: Totally, 334 individuals underwent an allergy work up regarding SARS‐CoV‐2 vaccination (group A: 115 individuals suspected to be at increased risk for vaccine‐related reactions before vaccination and group B: 219 patients with reactions after COVID vaccination). The large majority of the SPT/IDT with the vaccines were negative; however, we identified in 14.1% (n = 47) a possible sensitization to the SARS‐CoV‐2 vaccine and/or its ingredients defined as one positive skin test. Of the 219 individuals (group B) who experienced symptoms suspicious for a hypersensitivity reaction after vaccination, 214 were reported after the first vaccination with a mRNA vaccine (157 mRNA (Comirnaty®, 38 Spikevax®) and 18 with a vector vaccine (Vaxzevria®), 5 cases were after the second vaccination. Results: The symptom profile in group B was as follows: skin symptoms occurred in 115 cases (n = 59 angioedema, n = 50 generalized urticaria and n = 23 erythema/flush. Seventy individuals had cardiovascular, 53 respiratory and 17 gastrointestinal symptoms. Of the overall 334 individuals, 78 patients tolerated (re)‐vaccination (out of skin test positive/negative 7/19 from group A and 17/35 from group B). Conclusion: Proven IgE‐mediated hypersensitivity to SARS‐CoV‐2 vaccines is extremely rare and not increased in comparison with reported hypersensitivity to other vaccines. The value of skin tests is unclear and nonspecific reactions, in particular when intradermal testing is applied, should be considered. [ABSTRACT FROM AUTHOR]

Background: Essential oils (EOs) are widely used in cosmetics, perfumes, massage fluids, aroma therapy and natural medicine. Some EOs contain contact sensitizers. Objectives: To describe the frequency of sensitization to EOs in dermatitis patients presenting in skin clinics including concomitant reactions, to evaluate the EO patch test preparations and to identify patient groups with an increased risk of EO sensitization. Patients and methods: Retrospective analysis of data from the Information Network of Departments of Dermatology (IVDK), 2010–2019. Results: Twelve EOs were patch tested in an aimed manner in 10 930 patients, of whom 908 (8.3%) reacted to at least 1 EO. Only 6 EOs elicited more than 1% positive patch test reactions: ylang ylang (I + II) oil (3.9%), lemongrass oil (2.6%), jasmine absolute (1.8%), sandalwood oil (1.8%), clove oil (1.6%) and neroli oil (1.1%). Concomitant reactions among EOs or to EOs and fragrances were frequent. Among EO‐positive patients, women, leg dermatitis patients, patients aged 40 years or more, masseurs and cosmeticians were over‐represented. Conclusions: Sensitization to EOs occurs, albeit infrequently in most cases. Masseurs and cosmeticians have an increased risk of sensitization to EOs. [ABSTRACT FROM AUTHOR]

Summary: Contact dermatitis is an inflammation of the epidermis and dermis at the site of exposure triggered by external agents. The two main forms are irritant and allergic contact dermatitis, which cause significant health and socioeconomic costs in addition to a marked reduction in quality of life. The anamnesis and the clinical picture are decisive for the necessary diagnostic measures. The most accurate possible diagnostic classification of contact dermatitis by means of allergological testing is important for disease management, since not only classical eczema therapy but also avoidance of the exogenous triggering factors are of great importance here. The choice of therapy should be based on the acuity, clinical severity, morphology of the lesions and localization of the contact dermatitis. A combination of basic therapy, topical, physical, and systemic therapy adapted to the patient's needs is required, whereby not all forms of therapy must be carried out simultaneously but can be used in a varying manner. Primary, secondary, and tertiary prevention strategies aim at the recognition of the triggering noxae or allergens with subsequent contact avoidance or minimization. The present S1‐guideline on contact dermatitis is primarily intended to provide dermatologists, allergologists and physicians working in allergology and occupational dermatology with a decision‐making aid for the selection and implementation of suitable and sufficient diagnostics, therapy, and prevention. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Complex N -glycan modification of secretory glycoproteins in plants is still not well understood. Essential in animals, where a lack of complex N -glycans is embryo-lethal, their presence in plants seemed less relevant for a long time mostly because Arabidopsis thaliana cgl1 mutants lacking N -acetyl-glucosaminyltransferase I (GNTI, the enzyme initiating complex N -glycan maturation in the Golgi apparatus) are viable and showed only minor impairments regarding stress tolerance or development. A different picture emerged when a rice (Oryza sativa) gntI T-DNA mutant was found to be unable to reach the reproductive stage. Here, we report on tomato (Solanum lycopersicum) lines that showed severe impairments upon two RNA interference (RNAi) approaches. Originally created to shed light on the role of core α1,3-fucose and β1,2-xylose residues in food allergy, plants with strongly reduced GNTI activity developed necrotic fruit-attached stalks and early fruit drop combined with patchy incomplete ripening. Correspondingly, semiquantitative RT-PCR of the abscission zone (az) revealed an increase of abscission markers. Also, GNTI -RNA interference (RNAi) plants were more susceptible to sporadic infection. To obtain vital tomatoes with comparable low allergenic potential, Golgi α-mannosidase II (MANII) was chosen as the second target. The resulting phenotypes were oppositional: MANII-reduced plants carried normal-looking fruits that remained attached for extended time without signs of necrosis. Fruits contained no or only few, but enlarged, seeds. Furthermore, leaves developed rolled-up rims simultaneously during the reproductive stage. Trials to cross MANII-reduced plants failed, while GNTI-reduced plants could be (back-)crossed, retaining their characteristic phenotype. This phenotype could not be overcome by ethephon or indole-3-acetic acid (IAA) application, but the latter was able to mimic patchy fruit ripening in wild-type. Phytohormones measured in leaves and 1-aminocyclopropane-1-carboxylic acid (ACC) contents in fruits showed no significant differences. Together, the findings hint at altered liberation/perception of protein-bound N -glycans, known to trigger auxin-like effects. Concomitantly, semiquantitative RT-PCR analysis revealed differences in auxin-responsive genes, indicating the importance of complex N -glycan modification for hormone signaling/crosstalk. Another possible role of altered glycoprotein life span seems subordinate, as concluded from transient expression of Arabidopsis KORRIGAN KOR1-GFP fusion proteins in RNAi plants of Nicotiana benthamiana. In summary, our analyses stress the importance of complex N- glycan maturation for normal plant responses, especially in fruit-bearing crops like tomato. [ABSTRACT FROM AUTHOR]

Background: Omalizumab, a humanized recombinant monoclonal anti‐IgE antibody, proved to be effective in patients with chronic spontaneous urticaria (CSU), including severe and treatment‐refractory CSU. Here, we report omalizumab's effect on gene expression in skin biopsies from CSU patients enrolled in a double‐blind, placebo‐controlled study. Methods: Chronic spontaneous urticaria patients (18‐75 years) were randomized to either 300 mg omalizumab (n = 20) or placebo (n = 10) administered s.c. every 4 weeks for 12 weeks (NCT01599637). Lesional and nonlesional skin biopsies were collected from the same area of consenting patients and assessed at baseline and on Day 85 compared with skin biopsies from the same area of 10 untreated healthy volunteers (HVs). Gene expression data were generated using Affymetrix HG‐U133Plus2.0 microarrays. Statistical analyses were performed using R packages. Results: At baseline, 63 transcripts were differentially expressed between lesional and nonlesional skin. Two‐thirds of these lesional signatures were also differentially expressed between lesional and HV skin. Upon treatment with omalizumab, >75% of lesional signatures changed to reflect nonlesional skin expression levels (different vs placebo, P < 0.01). Transcripts upregulated in lesional skin (vs nonlesional and/or HV skin) suggested increased mast cell/leukocyte infiltration (FCER1G, C3AR1, CD93, S100A8, and S100A9), increased oxidative stress, vascularization (CYR61), and skin repair events (KRT6A, KRT16). Lesional signatures were not modulated by treatment in nonresponders (defined based on UAS7 longitudinal changes ≥16). Conclusion: Omalizumab, in treatment responders, reverted transcriptional signatures associated with CSU lesion phenotype to reflect nonlesional/HV expression levels; this is consistent with observed omalizumab‐mediated clinical improvement observed in patients with CSU. The gene expression of the lesional skin of patients with chronic spontaneous urticaria shows a distinct signature when compared to their nonlesional skin and the skin of healthy volunteers. The pattern of gene expression in the lesional skin of omalizumab‐treated patients are different than before treatment, but not in their nonlesional skin. In treatment responders, omalizumab treatment shows reverted transcriptional signatures associated with CSU lesion phenotype to reflect nonlesional/healthy volunteer expression levels consistent with observed clinical improvement. [ABSTRACT FROM AUTHOR]

We present the case of a 77-year-old female patient who suffered from severe anaphylaxis during wound care. Allergologic evaluation yielded specific IgE antibodies to chlorhexidine, but anaphylaxis to chlorhexidine was not congruent with the patient history and dermal provocation tests. However, skin prick tests provided evidence for a sensitization to polyhexanide that was further supported by the detection of specific IgE antibodies to polyhexanide, the results of basophil activation tests and IgE inhibition analysis. We presume cross-reactive IgE antibodies binding to both biguanide antiseptics and identified polyhexanide as the likely cause of the anaphylactic reaction. We recognize polyhexanide as an emerging allergen that has to be considered as a cause of anaphylaxis. [ABSTRACT FROM AUTHOR]

Aerogen lactase exposure carries a risk for the development of allergic asthma and rhinitis; only a few occupationally affected patients have been reported. The authors report the results of allergy testing with employees of a lactase tablets manufacturing plant. The survey involved 13 workers, including a questionnaire, spirometry, basophil activation test (BAT), and skin prick tests (SPTs) with lactase and a panel of common aeroallergens. Furthermore, lactase-specific immunoglobulin E (IgE) antibodies were analyzed. Sensitization to lactase could be proven for 9 workers by SPT and BAT; specific IgE antibodies could be detected in serum samples of all sensitized. However, IgE levels ≥0.35 kU/L were only found in 4 sera. These data confirm that occupational exposure to lactase can induce IgE-mediated respiratory sensitization resulting in allergic diseases. Protective measures should thus be obligatory when working with lactase. [ABSTRACT FROM AUTHOR]

Zusammenfassung Die Inzidenz allergischer Erkrankungen ist in den letzten Jahrzehnten dramatisch gestiegen, so dass diese Erkrankungen jetzt zu den 'Volkskrankheiten' gezählt werden müssen. Allergenexpositionsmeidung galt früher als wichtigste Maßnahme der primären Prävention. Zunehmend zeigen Studien, dass für die Entwicklung immunologischer Toleranz die Auseinandersetzung des Immunsystems mit Allergenen notwendig ist. Die Diagnostik basiert auf Anamnese, Hauttests und Bestimmung von spezifischen IgE-Antikörpern. Durch Komponenten-basierte Diagnostik kann eine primäre Sensibilisierung gegen eine Allergenquelle von Kreuzreaktionen durch Sensibilisierung gegen Panallergene oder kreuzreagierende Kohlenhydratepitope abgegrenzt werden. Die symptomatische Behandlung führt nur zu einer vorübergehenden Linderung der klinischen Beschwerden; durch spezifische Immuntherapie dagegen kann ein dauerhafter Effekt und möglicherweise eine Heilung erzielt werden. Die Auswahl von Allergenen für die spezifische Immuntherapie (SIT) wird durch das Leitallergenprinzip beeinflusst. Verwendet werden sollten Präparate, deren Wirksamkeit und Sicherheit in kontrollierten klinischen Studien belegt worden ist. Für die subkutane Immuntherapie stehen für eine Vielzahl von Allergenen geeignete und zugelassene Präparate zur Verfügung. Die Wirksamkeit der sublingualen Therapie ist insbesondere für Gräser- aber auch Baumpollenextrakte durch große klinische Studien belegt, so dass Präparate mit diesen Allergenen regulär zugelassen sind. [ABSTRACT FROM AUTHOR]

In recent decades, the incidence of allergic diseases has dramatically increased, by now affecting a large percentage of the population. For a long time, allergen avoidance was considered the most crucial measure in primary allergy prevention. However, studies have increasingly shown that exposure to allergens is an essential prerequisite for the development of immunological tolerance. Diagnostic workup is based on patient history, skin tests, and measurement of specific IgE antibodies. The introduction of component-based diagnostic workup offer an option to differentiate between primary sensitization and cross-reactivity caused by sensitization to panallergens or sensitization to cross-reactive carbohydrate epitopes. Symptomatic treatment only leads to temporary relief of allergic symptoms. By contrast, specific immunotherapy (SIT) may have long-lasting therapeutic effects and potentially even result in a complete cure. The selection of allergens for SIT is guided by the principle of major allergens. It is recommended to use those preparations that have been proven safe and effective in controlled clinical studies. With respect to subcutaneous immunotherapy, a host of tested and approved extracts are available for a wide range of different allergens. Large clinical trials have also confirmed the efficacy of sublingual immunotherapy with grass and also birch pollen extracts, which has led to the official approval of some preparations containing these allergens. [ABSTRACT FROM AUTHOR]

Background: It is estimated that up to 24% of the population in Germany suffers from allergic rhinoconjunctivitis and 5% from allergic asthma. Allergic rhinoconjunctivitis is closely related to other atopic diseases. Methods: This review is based on pertinent publications retrieved by a selective search of the Medline database, guidelines from Germany and abroad, and Cochrane metaanalyses. Results: Specific immunotherapy (SIT) is the only diseases-modifying treatment option for allergies. Metaanalysis reveals standardized mean differences in allergic rhinitis symptom scores of -0.73 for subcutaneous immunotherapy (SCIT) and -0.49 for sublingual immunotherapy (SLIT); the corresponding mean differences in medication scores are -0.57 and -0.32, respectively. The treatment should be carried out for at least three years. It is indicated when the symptoms are severe and allergen avoidance is not a realistic option. The efficacy of treatment depends on the allergen dose; thus, every allergen preparation should be evaluated individually, independent of route of administration. SCIT can cause systemic adverse effects, including anaphylaxis. SLIT is safer but often causes allergic symptoms of the oral mucosa at the beginning of treatment. Conclusion: Even though the efficacy of SIT is well documented, it is still underused. SIT should be offered as standard treatment to patients suffering from allergic rhinitis. [ABSTRACT FROM AUTHOR]

Summary Background: Pressure urticaria as a subform of physical urticaria is rare and treatment is often difficult. Established therapeutic regimes include antihistamines (generally exceeding approved dosages in order to achieve a therapeutic benefit) or antihistamines combined with montelukast. Complete relief of symptoms is difficult. Patients and methods: We used dapsone as an early therapeutic alternative in the event of treatment failure and established a standardized therapeutic regime at our clinic. We surveyed 31 patients retrospectively who had received dapsone between 2003-2009. Results: In 74 % of patients in whom symptoms persisted despite established therapies, the results of treatment with dapsone were good or very good. Longer-term pressure urticaria and the co-existence of a chronic spontaneous urticaria were associated with a smaller benefit (p<0.05). No significant effects were found related to age, gender, duration of therapy, side-effects, or Met-Hb elevation (a tendency toward a decreased benefit was associated with middle-age, male sex, shorter duration of therapy, observed side-effects, and Met-Hb elevation). Conclusions: Therapy is well tolerated and results in a good therapeutic benefit which lasts after termination of therapy. With adequate monitoring, the use of dapsone in patients with pressure urticaria has such a good risk-benefit ratio that we support early treatment initiation. [ABSTRACT FROM AUTHOR]

Chronic pruritus, which is associated with a wide variety of underlying diseases, represents a challenge in diagnostics and treatment in dermatology and general medicine. The cause of pruritus remains unknown in up to 45% of patients. In this study, 718 patients with chronic pruritus were analysed concerning lactase deficiency, demographic data, aetiology, duration and intensity of pruritus. A total of 154 patients were tested positive for lactase deficiency and 38.3% showed a significant anti-pruritic response to a lactose-free diet (minimum 4 weeks). The best results were observed in patients with pruritus of mixed or unknown origin (n = 91; 64% response). Age, sex, localization or duration had no significant influence on the anti-pruritic effect of a lactose-free diet. Lactase deficiency might be an independent causal factor in the elicitation of chronic pruritus. Thus, screening for lactase deficiency represents a rational step in the diagnostic work-up of chronic pruritus. In case of a positive test result, a lactose-free diet offers a low-cost, efficient and specific therapy in patients with chronic pruritus. [ABSTRACT FROM AUTHOR]

Background: In hymenoptera venom allergy, about 75% of detected in vitro double positivity to yellow jacket and honeybee venom is ascribed to specific IgE (sIgE) directed against cross-reactive carbohydrate determinants (CCDs). To date, for the detection of CCD-sIgE, different carbohydrate antigens and methods are used. The most suitable one still has to be identified. Methods: Eighty-seven patients with confirmed hymenoptera venom allergy and venom sIgE values of ≥0.7 kU/l were investigated. Sixty-five patients showed sIgE reactivity to both yellow jacket and honeybee venom, 22 were venom mono positive and served as controls. Occurrence of CCD-sIgE was determined using bromelain, horseradish peroxidase (HRP) and MUXF3 on system A, and ascorbic acid oxidase (AAO), bromelain and HRP on system B. Further, a reference standard for CCD-sIgE evaluation was created: CCD positivity was assumed when at least 4 of the 6 test results were positive. Results: According to the defined reference standard, 45/65 venom double positive patients exhibited CCD-sIgE. Using system A, comparison with the reference standard revealed sensitivity and specificity values of 96 and 97%, respectively, for MUXF3, 100 and 100%, respectively, for bromelain, and 96 and 97%, respectively, for HRP. Using system B, sensitivity and specificity was 98 and 97%, respectively, for AAO, 62 and 95%, respectively, for bromelain, and 96 and 69%, respectively, for HRP. Results of the 3 test allergens obtained with system A showed strong correlations (r = 0.932-0.976), whereas results with system B showed lower correlations (r = 0.714-0.898). Conclusions: All 3 test allergens used with system A are suitable for CCD-sIgE detection in hymenoptera venom allergy. With system B, only AAO seems to be a reliable tool. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: A longstanding debate in allergy is whether or not specific immunoglobulin-E antibodies (sIgE), recognizing cross-reactive carbohydrate determinants (CCD), are able to elicit clinical symptoms. In pollen and food allergy, ≳20% of patients display in-vitro CCD reactivity based on presence of α1,3-fucose and/or β1,2-xylose residues on N-glycans of plant (xylose/fucose) and insect (fucose) glycoproteins. Because the allergenicity of tomato glycoallergen Lyc e 2 was ascribed to N-glycan chains alone, this study aimed at evaluating clinical relevance of CCD-reduced foodstuff in patients with carbohydrate-specific IgE (CCD-sIgE). Methodology/Principal Findings: Tomato and/or potato plants with stable reduction of Lyc e 2 (tomato) or CCD formation in general were obtained via RNA interference, and gene-silencing was confirmed by immunoblot analyses. Two different CCD-positive patient groups were compared: one with tomato and/or potato food allergy and another with hymenopteravenom allergy (the latter to distinguish between CCD- and peptide-specific reactions in the food-allergic group). Nonallergic and CCD-negative food-allergic patients served as controls for immunoblot, basophil activation, and ImmunoCAP analyses. Basophil activation tests (BAT) revealed that Lyc e 2 is no key player among other tomato (glyco)allergens. CCDpositive patients showed decreased (re)activity with CCD-reduced foodstuff, most obvious in the hymenoptera venomallergic but less in the food-allergic group, suggesting that in-vivo reactivity is primarily based on peptide- and not CCDsIgE. Peptide epitopes remained unaffected in CCD-reduced plants, because CCD-negative patient sera showed reactivity similar to wild-type. In-house-made ImmunoCAPs, applied to investigate feasibility in routine diagnosis, confirmed BAT results at the sIgE level. Conclusions/Significance: CCD-positive hymenoptera venom-allergic patients (control group) showed basophil activation despite no allergic symptoms towards tomato and potato. Therefore, this proof-of-principle study demonstrates feasibility of CCD-reduced foodstuff to minimize 'false-positive results' in routine serum tests. Despite confirming low clinical relevance of CCD antibodies, we identified one patient with ambiguous in-vitro results, indicating need for further component-resolved diagnosis. [ABSTRACT FROM AUTHOR]