Cross-reactive Carbohydrate Determinants Research Articles

In-Depth Glycoproteomic Characterization of γ-Conglutin by High-Resolution Accurate Mass Spectrometry

The molecular characterization of bioactive food components is necessary for understanding the mechanisms of their beneficial or detrimental effects on human health. This study focused on γ-conglutin, a well-known lupin seed N-glycoprotein with health-promoting properties and controversial allergenic potential. Given the importance of N-glycosylation for the functional and structural characteristics of proteins, we studied the purified protein by a mass spectrometry-based glycoproteomic approach able to identify the structure, micro-heterogeneity and attachment site of the bound N-glycan(s), and to provide extensive coverage of the protein sequence. The peptide/N-glycopeptide mixtures generated by enzymatic digestion (with or without N-deglycosylation) were analyzed by high-resolution accurate mass liquid chromatography–multi-stage mass spectrometry. The four main micro-heterogeneous variants of the single N-glycan bound to γ-conglutin were identified as Man2(Xyl) (Fuc) GlcNAc2, Man3(Xyl) (Fuc) GlcNAc2, GlcNAcMan3(Xyl) (Fuc) GlcNAc2 and GlcNAc 2Man3(Xyl) (Fuc) GlcNAc2. These carry both core β1,2-xylose and core α1-3-fucose (well known Cross-Reactive Carbohydrate Determinants), but corresponding fucose-free variants were also identified as minor components. The N-glycan was proven to reside on Asn131, one of the two potential N-glycosylation sites. The extensive coverage of the γ-conglutin amino acid sequence suggested three alternative N-termini of the small subunit, that were later confirmed by direct-infusion Orbitrap mass spectrometry analysis of the intact subunit.

Cross-reacting carbohydrate determinants and hymenoptera venom allergy

Insect venom allergy is an important cause of anaphylaxis. Venom immunotherapy assume the clear identification of the culprit insect, but this is impeded by Immunoglobulin E (IgE) antibodies to cross reactive carbohydrate determinant (CCD) epitopes of common glycoproteins. Here we give an overview about inducers, importance, and relevance of anti-N-Glycan CCD IgE antibodies. Pollen exposure and insect stings induce anti-CCD IgE antibodies interfering with in-vitro tests for allergy diagnosis due to extensive IgE cross-reactivity. Instead of being biologically active these antibodies are irrelevant for allergic reactions due to hymenoptera stings. The general response of the immune system to the ubiquitous exposure to N-glycan containing glycoproteins is still a matter of debate. CCD specific IgG antibodies in sera of bee keepers suggest tolerance induction due to high-dose exposure. Tolerance induction by pollen and food glycoproteins has not been proved. Hymenoptera stings and pollen exposure induce anti-CCD IgE. In regard to anaphylaxis due to Hymenoptera stings these antibodies are not clinically relevant, but they are important for the specificity of in-vitro tests proving insect venom allergy. The introduction of component based diagnostic IgE testing improves the specificity of in-vitro tests if proteins devoid of CCD epitopes are used.

Reactions to honeybee stings

The purpose of this article is to provide a brief overview of the events involved in honeybee allergy and to concisely update the reader on progress toward knowledge of honeybee venom (HBV), strides in solving diagnostic difficulties, and advancements in improving safety and efficacy of HBV immunotherapy. It is well known that honeybee allergy is unique in venom allergen and protein composition, diagnostic challenges, and immunotherapy safety and efficacy. Many new honeybee allergens have been recognized. Advances in testing, evaluation, and extract manipulation methods, many using recombinant technology, have allowed a greater ability to help with honeybee allergy diagnosis and resultant improvement in immunotherapy safety and evaluation of immunotherapy efficacy. In an effort to address many honeybee allergy concerns, specific advances have been recently made. Some recently characterized honeybee allergens appear to be major contributors to honeybee allergy. In the setting of double-positivity, cross-reacting carbohydrate determinants and other cross-reacting components in HBV have made diagnosis of honeybee allergy challenging. Recombinant technology, including component-resolved diagnostics, and other evolving testing methods should help clarify double-positivity, if not now, in the very near future. Purified HBV and possibly depot formulations for immunotherapy appear to make it more well tolerated. Recombinant methods may help with evaluation of immunotherapy's safety and efficacy.

Peanut-specific IgE antibodies in asymptomatic Ghanaian children possibly caused by carbohydrate determinant cross-reactivity

BackgroundThe prevalence of peanut allergy has increased in developed countries, but little is known about developing countries with high peanut consumption and widespread parasitic infections.ObjectiveWe sought to investigate peanut allergy in Ghana.MethodsIn a cross-sectional survey among Ghanaian schoolchildren (n = 1604), data were collected on reported adverse reactions to peanut, peanut sensitization (serum specific IgE and skin reactivity), consumption patterns, and parasitic infections. In a subset (n = 43) IgE against Ara h 1, 2, 3, and 9 as well as cross-reactive carbohydrate determinants (CCDs) was measured by using ImmunoCAP. Cross-reactivity and biological activity were investigated by means of ImmunoCAP inhibition and basophil histamine release, respectively.ResultsAdverse reactions to peanut were reported in 1.5%, skin prick test reactivity in 2.0%, and IgE sensitization (≥0.35 kU/L) in 17.5% of participants. Moreover, 92.4% of those IgE sensitized to peanut (≥0.35 kU/L) had negative peanut skin prick test responses. Schistosoma haematobium infection was positively associated with IgE sensitization (adjusted odds ratio, 2.29; 95% CI, 1.37-3.86). In the subset IgE titers to Ara h 1, 2, 3, and 9 were low (<1.3 kU/L), except for 6 moderately strong reactions to Ara h 9. IgE against peanut was strongly correlated with IgE against CCDs (r = 0.89, P < .0001) and could be almost completely inhibited by CCDs, as well as S haematobium soluble egg antigen. Moreover, IgE to peanut showed poor biological activity.ConclusionsParasite-induced IgE against CCDs might account largely for high IgE levels to peanut in our study population of Ghanaian schoolchildren. No evidence of IgE-mediated peanut allergy was found.

Crystal structure and immunologic characterization of the major grass pollen allergen Phl p 4

Phl p 4 is a major pollen allergen but exhibits lower allergenicity than other major allergens. The natural protein is glycosylated and shows cross-reactivity with related and structurally unrelated allergens. We sought to determine the high-resolution crystal structure of Phl p 4 and to evaluate the immunologic properties of the recombinant allergen in comparison with natural Phl p 4. Different isoallergens of Phl p 4 were expressed, and the nonglycosylated mutant was crystallized. The specific role of protein and carbohydrate epitopes for allergenicity was studied by using IgE inhibition and basophil release assays. The 3-dimensional structure was determined by using x-ray crystallography at a resolution of 1.9 Å. The allergen is a glucose dehydrogenase with a bicovalently attached flavin adenine dinucleotide. Glycosylated and nonglycosylated recombinant Phl p 4 showed identical inhibition of IgE binding, but compared with natural Phl p 4, all recombinant isoforms displayed a reduced IgE-binding inhibition. However, the recombinant protein exhibited an approximately 10-fold higher potency in basophil release assays than the natural protein. The crystal structure reveals the compact globular nature of the protein, and the observed binding pocket implies the size of the natural substrate. Plant-derived cross-reactive carbohydrate determinants (CCDs) appear to reduce the allergenicity of the natural allergen, whereas the Pichia pastoris-derived glycosylation does not. Our results imply yet undescribed mechanism of how CCDs dampen the immune response, leading to a novel understanding of the role of CCDs.

Prevalence and peculiarities of IgE reactivity to kiwifruit pectin methylesterase and its inhibitor, Act d 7 and Act d 6, in subjects allergic to kiwifruit

Kiwifruit is an important cause of allergy. Although several allergens have been identified in this food (www.allergome.org), data on the number and clinical relevance of kiwifruit allergenic proteins are still fragmentary. With the aim of providing a contribution to the description of the complete kiwifruit allergome, we have investigated the immunological features of pectin methylesterase (PME) and its inhibitor (PMEI) purified from the natural source. Specific IgE to PME (Act d 7) and PMEI (Act d 6) were recorded in patients with kiwifruit allergies by immunoblotting, multiplex microarray-based immunoassay and skin testing (ST). Compared to the results obtained by the microarray system, the percentage of subjects detected positive to Act d 6 was much higher in the immunoblotting. Conversely, a similar percentage of subjects positive to Act d 7 was estimated in both the in vitro tests. Few subjects compared to in vitro testing gave a positive response on ST. In the case of Act d 7 this could be ascribed to the glycan side chain recognized by cross-reactive carbohydrate determinants (CCD)-specific IgE. In fact, Act d 7 fell in the cluster of glycoallergens (including Api m 1, Cup a 1, Hor v 17, Ole e 1, Pla a 2) immobilized on the microarray and recognized by CCD-specific IgE. A comparative analysis of different kiwifruit allergens (Act d 1, 2, 5, 6, 7, 11) revealed that only Act d 7 fell in this cluster, whereas Act d 2, although reported to be glycosylated, fell outside, thus suggesting the lack of sugars bound to this molecule. The subsequent biochemical characterization confirmed that Act d 2 is not a glycoallergen. In conclusion, Act d 7 and 6 seem to be rarely involved in causing symptoms in kiwifruit allergic patients. Nevertheless they are useful to understand a single patient profile and the mechanism of protein allergenicity. In addition, in this study the use of a multiplex test system has provided more information than expected, thus contributing to both the immunological and biochemical characterization of the immobilized allergens.

Isolated IgE reactivity to native walnut vicilin-like protein (nJug r 2) on ISAC™ microarray is due to cross-reactive carbohydrate epitopes

The last version of the microarray-based testing ImmunoCAP ISAC 112™ includes the native walnut (Junglans regia) molecules 2S albumin (nJug r 1), vicilin (nJug r 2) and lipid transfer protein (nJug r 3). In view of the many unexpected cases of isolated positivity to nJug r 2 occurring in daily practice, we evaluated the association of these reactivities with clinical symptoms, as well as the relationship between sIgE and nJug r 2 and cross-reactive carbohydrate determinants (CCDs). Sera from 320 consecutive allergic outpatients tested by ImmuoCAP ISAC™ 112 were considered. The medical records of all nJug r 2 positive patients were reviewed to assess clinical symptoms related to walnut allergy. A linear regression analysis was performed to evaluate the correlation between nJug r 2 and CCDs (nMUXF3) sIgE values, and a CAP inhibition assay was carried out to confirm the possible cross-reactivity between CCDs and nJug r 2. Thirty-seven out of 320 sera tested (11.6%) were positive to nJug r 2. Among them three (8.1%) and eight (21.6%) scored positive for nJug r 1 and nJug r 3 as well, respectively. Twenty-seven (73%) sera showed isolated nJug r 2 positivity. Only nJug r 1 reactors had symptoms referred to walnut allergy. Twenty-five/37 nJug r 2-positive sera (67.6%) showed a simultaneous positivity to nMUXF3 and a significant correlation (p<0.0001) between the IgE levels to nJug r 2 and nMUXF3 (r²=0.787). After incubation with nMUXF3 a complete inhibition of sIgE reactivity to both nMUXF3 and nJug r 2 was shown. The unexpected isolated sIgE reactivity to nJug r 2 found by ImmunoCAP ISAC™ 112 is frequently related to reactivity to cross-reactive carbohydrate epitopes and it is lacking clinical significance.

Unexpected death: Anaphylactic intraoperative death due to Thymoglobulin carbohydrate excipient

Anaphylactic shock is a life-threatening allergic response characterized by severe hypotension, inducing tissue hypoperfusion with possible multi-organ failure and death. We describe the first case of fatal intra-operative anaphylactic shock due to prolonged infusion of Thymoglobulin during Orthotopic Liver Transplantation (OLT), resulting from recruitment of both mastocytes and basophils, activated and degranulated. Post-mortem serological analysis on a preserved, pre-OLT sample of the patient's blood revealed specific IgE against carbohydrate cross-reactive determinants (CCDs), such as MUXF3 and nAna c2, proving that anaphylactic reaction was triggered by the Thymoglobulin carbohydrate excipient (sugar alcohol mannitol), rather than anti-thymocyte globulin itself. Our findings are consistent with scientific data reported in the literature, where only one case of non-fatal anaphylaxis to Thymoglobulin has been described, despite the existence of proven cases of anaphylactic reaction to mannitol. This case highlights the need to pay particular attention in future not only to active substances but also to drug excipients, above all during intra-operative drug delivery. In view of the important role played by basophils in this kind of anaphylaxis, the basophil activation test (BAT) could prove useful in preventing anaphylactic death from CCDs.

Microarray‐based component‐resolved diagnosis of latex allergy: isolated IgE‐mediated sensitization to latexprofilin Hev b8 may act as confounder

Immediate type allergy to latex is still a widespread problem. Latex-allergic patients undergoing diagnostic and operative medical procedures are at risk of potentially life-threatening reactions. Accurate diagnostic methods are therefore crucial. The aim of this retrospective study was to discriminate between sensitization and relevant allergy to latex based on an easy and suitable diagnostic approach. In 14 patients with clinical symptoms and 27 controls, latex skin prick tests (SPT), IgE against latex (CAP) and serological component resolved specific latex-allergen determination (Hev b1, b3, b5, b6, b7, b8, b9, b10, b11) based on ImmunoCAP ISAC were performed. SPT correlated very well with clinically manifest latex-allergy demonstrating a high specificity (95%) (and a low sensitivity). However, CAP levels to crude latex could not safely discriminate between purely sensitized and latex-allergic patients. The majority of patients mono-sensitized to the latex profilin Hev b8 did not suffer from any relevant symptoms upon contact with latex. However, in two patients with latex-allergy diagnosed by elevated specific IgE only sensitized against Hev b8, additional sensitization to carbohydrate cross-reactive determinants (CCD) was found. In the case of positive serum IgE against latex and negative SPT, component-resolved diagnosis including IgE against specific latex-proteins, specially Hev b8, and carbohydrate cross-reactive determinants (CCD) is a useful tool to discriminate between latex-sensitization and latex-allergy.

Spiking venom with rVes v 5 improves sensitivity of IgE detection in patients with allergy to Vespula venom

Spiking venom with rVes v 5 improves sensitivity of IgE detection in patients with allergy to Vespula venom

Sensitization to cross-reactive carbohydrate determinants in 2 patients with Hymenoptera venom allergy and alcoholic cardiomyopathy

Sensitization to cross-reactive carbohydrate determinants in 2 patients with Hymenoptera venom allergy and alcoholic cardiomyopathy

Cross‐reactive antigens for natural IgE antibodies: allergens with the potential to transform a dormant to an active allergic response?

Cross‐reactive antigens for natural IgE antibodies: allergens with the potential to transform a dormant to an active allergic response?

The major royal jelly proteins 8 and 9 (Api m 11) are glycosylated components of Apis mellifera venom with allergenic potential beyond carbohydrate‐based reactivity

As hymenoptera venoms are one of the allergen sources causing the highest incidence of anaphylaxis and sometimes fatal consequences, the detailed characterization of all venom allergens is imperative for design of component-resolved diagnostic approaches and improved intervention strategies. Our aim was the immunochemical characterization of major royal jelly proteins (MRJP) 8 and 9, both components identified in honeybee venom (HBV) and putative allergens. Both MRJPs were recombinantly produced as soluble differentially glycosylated proteins providing a defined degree of reactivity to cross-reactive carbohydrate determinants (CCD) in insect cells. Allergen-specific IgE(sIgE) reactivity of HBV-allergic patients was analysed by ELISA and immunoblotting. MRJP8 and MRJP9 were identified as venom components by MS-based proteomic analyses. In a population of 47 HBV-allergic patients, reactivities with CCD-carrying MRJPs were in the range of 56% (61%), underlining the contribution of CCDs to allergen-binding. Beyond CCD-reactivity, 15% of patients showed sIgE reactivity with MRJP8 and 34% with MRJP9 respectively. These reactivities roughly in the range of Api m 2 render the MRJPs minor, but important allergens. The glycosylated MRJP8 and MRJP9 of HBV have IgE-sensitizing potential in HBV-allergic patients beyond CCD reactivity and have to be considered as allergens, which might be potentially important for a fraction of venom allergic patients. They are valuable tools to elucidate individual component-resolved reactivity profiles of venom allergic patients and to provide insights into the role of particular venom components. Due to their allergenic properties, MRJP8 and MRJP9 were designated as isoallergens Api m 11.0101 and Api m 11.0201 respectively.

Double positivity to bee and wasp venom: Improved diagnostic procedure by recombinant allergen–based IgE testing and basophil activation test including data about cross-reactive carbohydrate determinants

Specific IgE (sIgE) antibodies to both bee and wasp venom can be due to a sensitivity to both insect venoms or due to cross-reactive carbohydrate determinants (CCDs). Investigating whether a basophil activation test (BAT) with both venoms as well as with bromelain and horseradish peroxidase (HRP) or recombinant allergen-based IgE testing can improve the diagnostic procedure. Twenty-two Hymenoptera-venom allergic patients with sIgE antibodies to both bee and wasp venom were studied. sIgE antibodies to MUXF3 CCD, bromelain, HRP, rApi m 1, and rVes v 5 were determined, and a BAT (Flow2 CAST) with venom extracts,bromelain, and HRP was performed. Further recombinant allergen-based IgE testing was done by using an ELISA, if required. The reactivity of basophils was calculated from the insect venom concentration at half-maximum stimulation. Double positivity/double negativity/single positivity to rApi m 1 and rVes v 5 was seen in 12/1/9 patients. Further recombinant allergen-based IgE testing in the last ones revealed positive results to the other venom in all cases except one. BAT was double positive/double negative/single positive in 6/2/14 patients. Four patients with negative results in sIgE antibodies to CCDs had positive results in BAT. BAT with bromelain/HRP showed a sensitivity of 50%/81% and a specificity of 91%/90%. Component-resolved IgE testing elucidates the pattern of double positivity, showing a majority of true double sensitizations independent of CCD sensitization. BAT seems to add more information about the culprit insect even if the true clinical relevance of BAT is not completely determined because of ethical limitations on diagnostic sting challenges. BAT with HRP is a good method to determine sensitivity to CCDs.

Differential IgE sensitization to cypress pollen associated to a basic allergen of 14 kDa

The common cypress (Cupressus sempervirens) (Cups) pollen represents the first cause of respiratory allergies in the Mediterranean basin. The aim of this study was to characterize a novel 14-kDa cypress pollen allergen (BP14) allowing a clear dissociation of IgE sensitization patterns among allergic patients. The biochemical and immunochemical characterization of BP14 included determination of its isoelectric point, molecular mass, extraction kinetics, IgE binding prevalence, the presence of bromelain-type cross-reactive carbohydrate determinant and its IgE reactivity under reducing conditions. The presence of potential cross-reactive homologues in closely related cypress species, i.e. Cupressus arizonica (Cupa) and Cryptomeria japonica (Cryj), as well as in several taxonomically unrelated species was also investigated. According to our results, BP14 is easily and quickly solubilized in phosphate-buffered saline and exhibits several allergenic isoforms covering a broad range of pI (6.5-10.5). This allergen displays heat-stable conformational epitopes and does not include cross-reactive carbohydrate determinants, in contrast to high molecular weight cypress allergens. BP14 is expressed at higher levels in Cups than in Cupa and Cryj. No IgE cross-reactivity was found between the 14-kDa Cups pollen protein and proteins from some other non-Cupressaceae pollen allergenic sources such as orchard, timothy, wheat, maize, birch, ash and pine. Thus, IgE reactivity to BP14 is specific to Cupressaceae and discriminates two groups of patients allergic to cypress pollen. It might correspond to a relevant marker in relation to the sensitization process and/or the symptoms observed in some cypress-pollen-allergic patients. Furthermore, the description of BP14 should improve the diagnosis of cypress pollinosis.

Rice-Induced Anaphylaxis: IgE-Mediated Allergy against a 56-kDa Glycoprotein

Background: Although rice (Oryza sativa) is one of the most common cereals produced and consumed around the world, there have been only a few reports on immediate hypersensitivity reactions after ingestion of rice. Few clinical studies on rice allergy in Asia have been reported concerning rhinitis, asthma and atopic dermatitis. In this case study, we identify allergens presumably responsible for anaphylaxis after ingestion of rice in a German patient. Methods: Prick-to-prick tests, determination of specific IgE and the basophil activation test (BAT) were performed to confirm IgE-mediated allergy. IgE reactivity was further analyzed by immunoblotting of protein extracts from cooked commercial rice products. Rice allergens were purified, subjected to N-terminal sequencing and characterized by IgE binding and IgE inhibition assays using additional sera from 8 subjects with sensitization to rice and/or a history of hypersensitivity symptoms after rice ingestion. Results: Prick-to-prick tests were positive to raw and cooked rice (basmati rice and long-grain rice) and preparations of different rice extracts. Specific IgE against rice (f9) was 1.87 kU_A/l. The BAT showed specific IgE-mediated activation of basophils after stimulation with rice extracts. Four IgE-reactive rice proteins with an apparent molecular weight of 49, 52, 56 and 98 kDa were identified. Interestingly, only binding to the 56-kDa glycoprotein was at least partially independent from cross-reactive carbohydrate determinants (CCD), whereas IgE binding to the other rice proteins was completely inhibited by pre-incubation with the CCD MUXF derived from bromelain. Conclusions: Yet unidentified high-molecular-weight allergens from rice seeds, predominantly a 56-kDa glycoprotein, seem to be responsible for anaphylaxis after consumption of rice in a German patient.

Value of component based diagnostics in IgE-mediated hymenoptera sting reactions

Background: Stings by insects can precipitate many signs and symptoms of dermatological and ocular diseases. Of particular importance is the anaphylaxis after Hymenoptera stings. Selection of the appropriate venom for immunotherapy requires a precise diagnosis, which is frequently difficult to confirm since the history presented by the patient is many times not conclusive and diagnostic tests are often positive for bee venom (BV) and vespula venom (VV). This double positivity is either caused by true double sensitization or by antibodies cross-reactive to homologous peptide sequences or to cross-reactive carbohydrate determinants (CCDs). In this study, we analyzed in 39 patients, tested positive for specific immunoglobulin E (sIgE) against BV and VV and CCDs whether the routine detection of sIgE against the recombinant species-specific major allergens (SSMAs) rApi m1 and rVes v5 enables the discrimination between genuine double sensitization and cross reactivity and therefore may be superior to other in vitro assays such as IgE-inhibition test or the basophil activation test.Materials and methods: Thirty-nine patients each with allergic reactions to vespula and/or honey bee stings and tested positive for sIgE antibodies against CCDs were analyzed for sIgE against BV, VV, CCDs (MUFX3) and SSMAs by UNICAP (CAP) and to BV, VV, bromelain, horseradish peroxidase and ascorbat oxidase by Immulite 2000 (IMMU). In 12 cases results from a basophil activation test, in nine cases results from IgE-inhibition assays and in 10 cases an unambiguous history of the patient were taken into consideration.Results: A definite diagnosis could be assigned to each patient: sensitization to BV n = 7, sensitization to VV n = 29 and true double sensitization to both venoms n = 3. Detection of sIgE against BV and VV by CAP leads in three cases to the diagnosis BV allergy, in 35 cases to the diagnosis double sensitization and in one case to the diagnosis VV allergy. Detection of sIgE against BV and VV by IMMU leads in five cases to the diagnosis BV allergy, in 27 cases to the diagnosis double sensitization and in seven cases to the diagnosis VV allergy. Detection of sIgE against rApi m1 and rVes v5 by CAP leads in six cases to the diagnosis BV allergy, in eight cases to the diagnosis double sensitization, in 21 cases to the diagnosis VV allergy and in four cases to a false double-nagative result implicating no allergy.Discussion and conclusion: Detection of sIgE to rApi m 1 and rVes v 5 by CAP is the most reliable diagnostic procedure to discriminate between true double sensitization and cross reactivity in patients with double-positive IgE results to venom extracts in the presence of sIgE against CCDs. In this study, however, we demonstrate that in nine of 39 patients tested positive for sIgE against CCDs, even the allergen component based diagnostic produces false double-positive and also false double-negative test results. Thus, we conclude that especially in hard to diagnose CCD positive patients beside the detection of sIgE, in vitro assays such as the IgE-inhibition test or the basophil activation test are still of importance. Detection of sIgE against only two SSMAs is not sufficient for a precise diagnosis. We propose inclusion of further SSMAs in diagnostic procedures.

Minor Interference of Cross-Reactive Carbohydrates with the Diagnosis of Respiratory Allergy in Standard Clinical Conditions

Background: Immunoglobulin E (IgE) to N-glycans from plant and invertebrate glycoproteins induces extensive in vitro cross-reactivity. This study investigates the prevalence and diagnostic relevance of IgE to these N-glycans [cross-reactive carbohydrate determinants (CCDs)] in patients with suspicion of respiratory allergy. Methods: A total of 1,025 adult subjects with symptoms of rhinitis and/or asthma from a reference allergy clinic were studied. Determinations included a structured questionnaire, skin prick tests (SPT), total IgE, a multiallergen IgE test and specific IgE (sIgE) to bromelain, MUXF (the bromelain-type N-glycan) and honeybee phospholipase-A2. Inhibition studies with CCDs were performed in selected cases. Results: The prevalence of CCD sensitization (MUXF sIgE and/or bromelain-sIgE ≧0.1 kU_A/l) was 18.0%. Male sex and atopy (SPT positivity) were associated with CCD sensitization. Sensitization was more frequent in patients sensitized to pollens than in those sensitized to mites, the most common inhalant allergens in the area. A history of Hymenoptera stings was associated with CCD sensitization and multiallergen IgE test positivity. CCD sensitization was not significantly associated with age, rural residence, alcohol consumption or smoking. Only 58 patients (5.6%) showed CCD-sIgE levels ≧0.35 kU_A/l. CCD-induced inhibition of pollen-sIgE or mite-sIgE in patients with respective positive SPT was minimal or absent in most cases. Conclusions: In this population of predominantly mite-allergic patients, CCD sensitization is relatively rare and CCD-sIgE levels are low. Thus, CCDs do not represent a major obstacle for the diagnosis of respiratory allergy in a specialized setting. Hymenoptera stings are associated with CCD sensitization.

Low prevalence of IgE to cross-reactive carbohydrate determinants in beekeepers

Low prevalence of IgE to cross-reactive carbohydrate determinants in beekeepers

Evaluation of IgE Antibodies to Recombinant Peanut Allergens in Patients with Reported Reactions to Peanut

Background: Peanut may cause severe reactions in allergic individuals. The objective was to evaluate IgE antibodies to various recombinant (r) peanut and birch pollen allergens in relation to IgE levels to whole peanut extract and severe allergic reactions to peanut. Methods: Seventy-four Swedish peanut-allergic patients (age: 14–61 years) reported previous peanut exposure and associated symptoms using a questionnaire. Their IgE reactivity to peanut, birch pollen and individual allergen components was analyzed using ImmunoCAP®. Results: Of the 48 subjects sensitized to Ara h 1, 2 or 3, 60% had peanut-specific IgE levels >15 kU_A/l, while 100% of the subjects without detectable IgE to these allergens had low peanut-specific IgE levels (<10 kU_A/l). The levels of IgE to rAra h 8, rBet v 1 and birch pollen were highly correlated (r_S = 0.94, p < 0.0001). Fifty-eight patients reported adverse reactions after accidental or deliberate peanut exposure (oral, inhalation or skin) of whom 41 had IgE to rAra h 1, 2 or 3. Symptoms of respiratory distress were associated with sensitization to Ara h 1, 2 or 3 (56 vs. 18%, p < 0.01). Two cases of anaphylaxis were reported among the individuals sensitized to Ara h 1–3. IgE to rAra h 8, rAra h 9, profilin or cross-reactive carbohydrate determinants were not associated with severe symptoms. Conclusions: The results indicate that IgE reactivity to Ara h 1, 2 and 3 is associated with severe reactions after exposure to peanut in Swedish patients.