Cross-reactive Carbohydrate Determinants Research Articles

On the cause and consequences of IgE to galactose-α-1,3-galactose: A report from the National Institute of Allergy and Infectious Diseases Workshop on Understanding IgE-Mediated Mammalian Meat Allergy

The mammalian meat allergy known as the "α-Gal syndrome" relates to IgE specific for galactose-α-1,3-galactose (α-Gal), an oligosaccharide that is present in cells and tissues of nonprimate mammals. The recognition of delayed reactions to food derived from mammals in patients with IgE to α-Gal and also the association with tick bites have been increasing worldwide. In 2018, the National Institute of Allergy and Infectious Diseases, Division of Allergy, Immunology and Transplantation, sponsored a workshop on this emerging tick-related disease. International experts from the fields of tick biology, allergy, immunology, infectious disease, and dermatology discussed the current state of our understanding of this emerging medical condition. The participants provided suggestions for specific research priorities and for the development of resources to advance our knowledge of the mechanisms, diagnosis, management, and prevention of this allergic disease. This publication is a summary of the workshop and the panel's recommendations are presented herein.

Alpha-Gal and Cross-Reactive Carbohydrate Determinants in the N-Glycans of Salivary Glands in the Lone Star Tick, Amblyomma americanum.

Ticks are important ectoparasites and vectors of numerous human and animal pathogens. Ticks secrete saliva that contains various bioactive materials to evade the host defense system, and often facilitates the pathogen transmission. In addition, the Lone star tick saliva is thought to be the sensitizer in red meat allergy that is characterized by an allergic reaction to glycan moieties carrying terminal galactose-alpha-1,3-galactose (aGal). To assess N-glycome of Amblyomma americanum, we examined the N-glycan structures in male and female salivary glands at three different feeding stages and in carcasses of partially fed lone star ticks. We also surveyed the genes involved in the N-glycosylation in the tick species. The aGal epitopes and cross-reactive carbohydrate determinants (CCD) increases over time after the onset of blood feeding in both male and female A. americanum. These CCDs include xylosylation of the core mannose, 1,3-mono and 1,3- and 1,6-difucosylations of the basal GlcNac and mono- or diantennary aGal. Combinations of both xylosylation and aGal and fucosylation and aGal were also found on the N-glycan structures. While the enzymes required for the early steps of the N-glycosylation pathway are quite conserved, the enzymes involved in the later stages of N-glycan maturation in the Golgi apparatus are highly diverged from those of insects. Most of all, we propose that the aGal serves as a molecular mimicry of bioactive proteins during tick feedings on mammalian hosts, while it contributes as a sensitizer of allergy in atypical host human.

N-Glycan Inhibitors in Immunoassay Methods for serum Allergen Specific IgE

Cross-reactive carbohydrate determinants (CCDs) represent fucosylated/xylosylated N-glycans present in pollen and food of plant origin, latex and hymenoptera venoms. IgE antibodies against CCD do not have significant clinical relevance, but represent an important cause of cross-reactivity in the case of in vitro immunoassay methods for determining serum specific IgE. CCD inhibitors play a key role in the laboratory for preventing misinterpretation of such in vitro positive assays and for increasing their specificity.

False-Positive Results of Serological Tests for Allergy in Alcoholic Patients.

Alcohol consumption is associated with enhanced TH2 immune responses. Objective: To investigate the frequency of false-positive results in serological tests for allergy in alcoholic patients. A total of 138 alcoholic patients consecutively admitted to hospital underwent a panel of allergy tests that included serum total IgE, a multiallergen IgE test (UniCAP Phadiatop), and skin prick tests to relevant aeroallergens in the area, which were considered the standard reference for atopy. In selected cases with positive specific IgE (sIgE) to cross-reactive carbohydrate determinants (CCDs) on ImmunoCAP, we determined sIgE to hymenoptera venom components (ADVIA Centaur) and a microarray of 103 allergen components (ISAC). Increased serum total IgE (>170 IU/mL) was observed in 59/110 (54%) of nonatopic (skin prick test-negative) patients. The result of the multiallergen IgE test was positive in 46 nonatopic patients (42%). This finding was closely associated with high serum concentrations of total IgE and sIgE to CCDs. The vast majority of patients with positive CCD-sIgE showed positivity to glycosylated plant and hymenoptera allergen components on ISAC and ADVIA Centaur. Only 1 out of 26 patients with positive sIgE to CCD and hymenoptera venom developed honeybee venom allergy after a median follow-up of 166 months. Correlations between measurements of sIgE to CCD markers on ImmunoCAP, ADVIA Centaur, and ISAC were imperfect. Serological tests for allergy should be interpreted with caution in alcoholic patients, who frequently have increased levels of total IgE and CCD-sIgE and subsequent positivity of sIgE to glycosylated allergen components, irrespective of the method used.

Agreement of serum allergen test results with unblocked and blocked IgE against cross‐reactive carbohydrate determinants (CCD) and intradermal test results in atopic dogs

Tests for allergen-specific immunoglobulin E (IgE) are used to select allergens for immunotherapy in atopic dogs. Antibodies against cross-reactive carbohydrate determinants (anti-CCD IgE) have been identified in serum samples of atopic dogs. Their presence in humans is a known cause of clinically irrelevant polysensitization to plant allergens. To compare the results of an intradermal test (IDT) and a serum test for allergen-specific IgE, with and without blocking anti-CCD IgE, before testing in dogs. Thirty-one privately owned dogs with atopic dermatitis. Dogs were prospectively skin tested and their serum samples were analysed for anti-CCD IgE. An Fc-ε receptor-based serum test for allergen-specific IgE was performed with and without blocking anti-CCD IgE. In dogs with negative anti-CCD IgE samples, the agreement between the results of the serum test and the IDT was substantial (κ=0.71). Dogs with positive anti-CCD IgE samples (38.7%) showed no agreement between serum and skin testing (κ=-0.35), blocking anti-CCD IgE in those samples resulted in a fair agreement (κ=0.43). Anti-CCD IgE positive sera had multiple positive results for grass and weed allergens, and blocking decreased them markedly. Intradermal testing agreed best with serum testing in dogs with no detectable anti-CCD IgE. Sera containing anti-CCD IgE had no agreement with IDT. Test agreement was improved by blocking the anti-CCD IgE. Apparent serum test polysensitization to plant allergens was associated with anti-CCD IgE.

The Clinical Relevance of Natural Rubber Latex-Specific IgE in Patients Sensitized to Timothy Grass Pollen

Background: In pollen-allergic patients, cross-reacting allergens including cross-reactive carbohydrate determinants (CCDs) and profilins may result in positive natural rubber latex (NRL)-specific IgE (sIgE) antibody tests but the relationship between this sensitization and clinical NRL type 1 allergy is poorly described. Objective: The aims of this study were to determine the frequency and clinical relevance of NRL sIgE in grass pollen-sensitized individuals and to investigate which NRL allergen components these individuals were sensitized to. Methods: A total of 383 grass-sensitized patients answered questions about NRL allergy symptoms and their stored sera from previous investigations were analyzed for NRL sIgE. Patients with NRL sIgE (n = 32) underwent further investigations comprising medical history, skin prick test with NRL and inhalational allergens, and an additional blood sample. The additional blood samples were analyzed for total IgE and sIgE against NRL, timothy grass, birch, rHev b 1, 3, 5, 6.01, 6.02, 8, 9, 11, rPhl p 12, and MUXF3, which was used as a marker of CCD sensitization. Results: Overall, 9.4% of all grass pollen-sensitized individuals showed IgE sensitization to NRL but only 1.6% had a confirmed type I NRL allergy. CCD and Hev b 8 explained the clinically irrelevant NRL IgE sensitization in 65% of the cases. We found a highly significant correlation between NRL profilin (Hev b 8) sensitization and grass profilin (Phl p 12) sensitization (p < 0.0001). Conclusions: Data from this study support the hypothesis that in patients with grass pollen sensitization, Hev b 8 mono-sensitization has little or no clinical relevance and is caused by cross sensitization from grass profilin (Phl p 12).

Cross-Reactive Carbohydrate Determinants (CCDs) Interference with Component Resolved Diagnosis on NOVEOS™*, ImmunoCAP® and IMMULITE® 2000.

Allergen specific IgE (sIgE) can bind CCD structures on plant and insect glycoproteins as well as peptide epitopes. These carbohydrate structures can display structural homology across many allergen groups leading to extensive cross-reactivity, obscure in vitro diagnostic results, and debatable clinical relevance. With the introduction of Component Resolved Diagnosis (CRD), non-glycosylated components can be utilized to prevent the detection of anti-CCD IgE and may improve clinical relevance. The aim of this study is to confirm anti-CCD IgE will not be detected on non-glycosylated components on NOVEOS, ImmunoCAP, and IMMULITE 2000. A panel of CCD-positive samples was selected based on their reactivity to several recombinant components. Samples were tested before and after inhibition with a commercially-available CCD inhibitor on NOVEOS, ImmunoCAP, and IMMULITE 2000. ImmunoCAP IgE binding was reduced by samples pre-incubated with a CCD inhibitor while NOVEOS and IMMULITE 2000 resulted in minimal reduction. The reduction of IgE binding to a non-glycosylated recombinant component from samples with a CCD inhibitor on ImmunoCAP suggests trace amount of CCD are still present in the test. This confirms other studies that have indicated the cellulose used as an allergen carrier on ImmunoCAP may elevate specific IgE result. NOVEOS, a microparticle-based chemistry, and IMMULITE 2000, bead-based technology, resulted in minimal IgE reduction with and without CCD inhibitor.

Allergen Recognition Patterns in Walnut Allergy Are Age Dependent and Correlate with the Severity of Allergic Reactions

Walnut is an important elicitor of food allergy in children and adults with a high rate of severe reactions. Multicenter studies using a common clinical protocol and a comprehensive allergen are lacking. To investigate potential correlations between molecular sensitization patterns and clinical characteristics of walnut-allergic patients. A total of 91 walnut-allergic subjects and 24tolerant controls from Switzerland, Germany, and Spain were included. Walnut allergy was established by food challenge in all but anaphylactic subjects. Specific IgE (sIgE) to walnut extract, rJug r 1 (2S albumin), rJug r 3 (nonspecific lipid transfer protein 1), nJug r 4 (11S globulin), rJug r 5 (PR-10 protein), 2vicilin fractions, profiling, and cross-reactive carbohydrate determinant was determined by ImmunoCAP. A threshold of 0.10 kUA/L was used for positivity. Sensitivity of sIgE to walnut extract was 87% and increased to 96% for the sum of all walnut components. sIgE to walnut extract and all walnut components, except rJug r 5, was significantly higher in patients younger than 14 years at inclusion. Stratification by age at onset of walnut allergy led to similar results. All patients younger than 14 years had severe reactions, whereas 38% of patients 14 years or older were mild reactors. Severe reactors (n= 70) had higher sIgE levels than did mild reactors (n= 21) to walnut extract (P < .0001), rJug r 1 (P<.0001), nJug r 4 (P= .0003), and both vicilin fractions (P<.0001), but not to Jug r 3 and Jug r 5. Sensitization to walnut storage proteins is acquired in childhood and correlates with severe reactions. sIgE levels to storage proteins Jug r 1 and Jug r 4 and vicilin fractions, but not to nonspecific lipid transfer protein and PR-10 proteins, correlate with systemic reactions to walnut.

Triple IgE-positivity to hornet, wasp and bee venom in the patient with anaphylaxis: Diagnostic and therapeutic approach

Introduction. Triple-positivity (TP) or double-positivity (DP) for serum-specific immunoglobulin E (sIgE) antibodies against hornet venom (HV), wasp venom (WV) and/or honeybee venom (BV) causes significant problem in a selection of appropriate venom immunotherapy. However, DP/TP can be caused by cross-reactions resulting either from partial sequence identity of protein allergens in the venoms, or may be related to cross-reacting carbohydrate determinants (CCDs). Case report. A 60-year-old man was stung by a wasp and two days later by hornet. In both cases, within 15 minutes he developed hypotension and generalized urticaria and he was successfully treated with epinephrine, corticosteroids and fluids. After eight weeks, the examination revealed the negative skin prick test for all three venoms, but the sIgE-determination (ELISA, Biopharm) showed triple sensitization to native BV (0.55 IU/mL), WV (3.35 IU/mL) and HV (0.37 IU/mL). He was receiving the venom immunotherapy with venom mixtures for one year. In order to distinguish true multiple sensitization from cross-reactivity, the molecular-allergy testing by ImmunCAP with the CCD-free recombinant major allergens was performed. A high sensitization to Antigen 5-rVes v5 of WV (31.4 kU/L) was demonstrated while sIgE to phospholipase A2-rApi m1 of BV (0.15 kU/L) was negative; sIgE to CCDMUXF3- bromelain (0.75 kU/L) explained the sIgE-positivity for native BV. After these findings, a venom immunotherapy only with WV was initiated. Conclusion. In our patient, triple-IgE-positivity to native venoms detected by the ELISA was caused by cross-reactivity to CCDs. We recommend the molecular-allergy testing with the nonglycosylated recombinant allergens before starting the venom immunotherapy in patients with multiple-sIgE-positivity to native Hymenoptera venoms.

A pilot study on the allergen-specific IgE to molecular components on polysensitized mite allergic asthmatic patients in Guangzhou, China

ObjectiveUsing multiplex microarray-based component resolved diagnosis (CRD) to investigate the allergen sensitization profile of allergic asthma patients in southern China. MethodSerum samples from 57 polysensitized mite allergic asthmatic patients in a tertiary referral centre of southern China were tested with multiplex CRD (ISAC) for specific immunoglobulin E (sIgE) against 112 single allergen and components. Result was then compared with those from singleplex ImmunoCAP. ResultsWith ISAC, the highest sensitization was seen for nDer f 1 (71.9%), rDer f 2 (73.7%), nDer p 1 (70.2%) and rDer p 2 (66.7%), whereas rDer p 10 and other storage mites’ components only showed 10% positivity. rFel d 1 and rCan f 1 were found positive in 29.8% and 14.0% samples respectively. Other epithelia components had less than 7.0% positive rate. Sensitization to pollen components was dominated by nCyn d 1 (17.5%) and nPhl p 4 (12.3%), Carbohydrate cross-reactive determinants (CCD) was positive in 4 patients who were also positive to nPhl p 4, nCyn d 1 and rPla a 2, and all of them have combined asthma and rhinitis. The sensitivity to mold (rAsp f 3), cockroach (nBla g 7) and Anisakis simplex component (rAni s 3) were all the same at 8.8%. 93.0% patients were sensitive to more than one component, with more than half of them (57.9%) positive to five or more components.Patients with combined asthma and rhinitis (AA + AR) were sensitive to more components than those with asthma only (AA). Positive rate to nPhl p 4 was significantly higher in patients with AA + AR than with AA only (χ2 = 4.31, P = 0.038).Compared with ImmunoCAP, ISAC showed a similar high detection rate for D. pteronyssinus and D. farinae, but only 10.0% of B. tropicalis sensitive patients were positive to rBlo t 5. Optimal scale analysis on correlation of allergens components showed rDer p 10 was associated to food allergy. ConclusionBeing the first multiplex microarray based CRD study on southern Chinese, ISAC showed house dust mites components were the major allergen components led to sensitization in asthmatic patients. Patients with combined AA + AR were sensitive to more components than those with AA only. Other components with higher positive rate include pollen components nCyn d 1, nPhl P 4 and animal dander components rFel d 1 and rCan f 1. For B. tropicalis, the rBlo t 5 in ISAC may not represent the major Blomia component in southern Chinese patients.

EPIDEMIOLOGICAL ASPECTS OF CCD-POSITIVITY IN PATIENTS WITH CLINICAL MANIFESTATIONS OF ALLERGY IN THE SOUTH-WESTERN REGION OF UKRAINE

Patients with antibodies to CCD, when tested for the presence of specific IgE antibodies to allergen extracts, may exhibit a large number of positive reactions.Objective - to determine the epidemiological aspects of CCD-positivity in patients with clinical manifestations of allergy in the South-Western region of Ukraine.Material and methods. Results of serological examination of 500 patients with allergic manifestations were estimated and antibodies to different carbohydrate determinants using CCD blot determined.Results. It has been shown that antibodies to cross-reactive carbohydrate determinants are detected in 17.8±1.71% of patients with clinical manifestations of allergy. Antibodies to CCD are recorded in 10.71±2.20%, of patients aged 0-10 years, they are significantly higher in patients older than 10 years, on the average 22.00±5.45%. A direct correlation relationship (r=0.88) was determined between the class of reaction to CCD and the number of positive reactions to allergens. In the group of patients with multiple allergen reactions, 73.7±7.14% showed positive reactions to different CCD chains during additional examination on the linear CCD blot. In a separate analysis of CCD-positive patients on the linear CCD-blot, it was shown that antibodies to horse radish peroxidase were significantly higher than to bromelain (p&lt;0.01) and ascorbate oxidase (p&lt;0.05). The same pattern was observed in patients with multiple allergen reactions. Conclusions. The results of the studies indicate that it is necessary to take into account the possibility of non-specific reactions related to cross-reactive carbohydrate determinants and additionally test patients for the presence of antibodies to CCD, especially in the case of multiple reactions to allergens.

SERUM IGE REACTIVITY TO CROSS-REACTING MOLECULES IN POLLEN ALLERGIC PATIENTS FROM NORTH EASTERN POLAND

Introduction Presence of IgE which cross-react with allergen components such as profilins, polcalcins and cross-reacting carbohydrate determinants (CCD) creates a problem in selection of patients for allergen immunotherapy. This study assesses the prevalence of sensitization to profilins, polcalcins and CCDs in seasonal allergic rhinitis patients (ARs). Methods 112 allergic rhinitis (AR) patients age 14 to 55 years with sensitization to at least one seasonal allergen (IgE>0.7 KU/l) were studied. IgE sensitization to recombinant(r) Bet v 2, rPhl p 12, rBet v 4, rPhl p 7 and CCDs in addition to rBet v 1, rPhl p 1, rPhl p 5 was evaluated using a multiplex immunoblot (Euroimmun, Germany). Results 64.3%, 80.4% and 41.1% of AR patients were sensitized to birch, timothy grass and mugwort pollen, respectively. Sensitization to rBet v 2/Phl p 12 occured in 26.8%, to Bet v 4/Phl p 7 in 8.9%, and to CCDs in 25%. In 29.3% of AR patients serum IgE reactivity to any of the cross-reactive component could be demonstrated. Serum IgE reactivity to rBet v 2 was always accompanied by reactivity to rPhl p 12 and reactivity to rBet v 4 was always accompanied by reactivity to rPhl p 7. Conclusions Evaluation of serum IgE reactivity to cross-reactive components may be useful in assessment of AR patients qualified for allergen immunotherapy.

Sensitization to Hymenoptera venom marker allergens: Prevalence, predisposing factors, and clinical implications.

The prevalence and predisposing factors of asymptomatic sensitization to Hymenoptera venom marker allergens are largely unknown. To evaluate sensitization profiles in a group of 490 dermatologic patients without a history of sting-induced anaphylaxis. Clinical data were collected using a structured questionnaire; sera were tested for total IgE and specific IgE to venom preparations, recombinant venom marker allergens, inhalative allergens, and cross-reactive carbohydrate determinants. The lifetime prevalence of Hymenoptera stings was 85.3%. IgE rates exceeding cut-off values of 0.35kUA /L were 17.3% for rVes v 1, 18.0% for rVes v 5, and 3.5% for rApi m 1. Median specific/total IgE ratios for the above mentioned marker allergens were 0.05%, 0.02%, and 0.00%, respectively. Marker allergen-directed sensitization was detectable in 85.5% of 138 Vespula venom-reactive sera. Of 68 bee venom-reactive participants, 23.5% were sensitized to rApi m 1 and 64.7% to any one or several of five commercially available bee venom allergens. Although double reactivity to bee and Vespula venom was clearly associated with sensitization to cross-reactive carbohydrate determinants (P<0.001), sensitization to marker allergens of both species was detectable in most double-reactive sera (56.5%). Vespula venom marker allergen-directed sensitization was associated with recent stings (P=0.010), large local reactions (P=0.009), total IgE elevation (P<0.001), and sensitization to cross-reactive carbohydrate determinants (P=0.008). The high sensitization rates observed in individuals without a history of sting-induced anaphylaxis as well as total IgE levels and cross-reactive carbohydrate determinant-directed reactivity as potential confounders need to be considered in any interpretation of positive test results for Hymenoptera venom marker allergens.

NCup a 1 as a marker of allergy to cypress pollen

The increase in polysensitisations among allergic patients has led us to search for suitable means of diagnosis for identifying true sensitisation, and distinguishing true sensitisation from cross-reactivity. Cross-reactive carbohydrate determinants (CCDs) present in glycoproteins from cypress pollen extracts have been linked with such cross-reactivity, particularly in in vitro assays. The application of component-resolved diagnosis using recombinant allergens makes it possible to identify true allergens. The problem arises when the allergen available for the usual diagnostic methods, which are used as a reference for the diagnosis of allergy to cypress pollen nCup a 1, is a native allergen. The aim of the study was to validate the native allergen nCup a as a marker of true sensitisation to cypress pollen. The sera of 96 subjects with a proven allergy to cypress pollen were analysed. We then quantified IgE specific to Cupressus arizonica and to nCup a 1 and also analysed the CCDs in subjects sensitised to several tree pollen allergens, presenting with MUXF3-specific IgE. Results revealed that there is a statistically significant correlation between conventional diagnostic techniques used to determine allergy to cypress pollen (SPT and IgE Cupressus arizonica) and sensitisation to nCup a 1. CCD quantification in subjects sensitised to several tree pollen antigens showed that these did not interfere with our results. We validated the native Cupressus arizonica allergen, nCup a 1, as a marker of allergy to cypress pollen in our population.

Grass-Allergic Children Frequently Show Asymptomatic Low-Level IgE Co-Sensitization and Cross-Reactivity to Wheat

Background: Specific immunoglobulin E (IgE) sensitization to wheat is more common than a doctor’s confirmed wheat allergy and is also frequently observed in grass pollen-allergic patients (pollinosis patients). Thus, the objective of this study was to investigate the level and feature of serological IgE cross-reactivity between grass pollen and wheat in a cohort of pollinosis subjects with no diagnosis of wheat allergy. Methods: Seventy-two children, aged 5–17 years, with a doctor’s diagnosis of pollinosis, IgE towards grass pollen, and currently eating wheat were recruited. Serum samples were analyzed for IgE against wheat, timothy grass/wheat-specific allergen components, Pru p 3, and cross-reactive carbohydrate determinants (CCD) and specific IgE-binding inhibition experiments were performed. Results: Sixty percent of the grass pollen subjects were sensitized to wheat with a median of 0.5 kU_A/L. Wheat-sensitized subjects were more often sensitized to the two allergens, Phl p 12 and CCD, known to be cross-reactive between grass and wheat. Sensitizations to seven wheat-specific allergens derived from the gluten fraction were, with the exception of one individual, only found in wheat-sensitized subjects. These subjects also more often reported current and past history of allergy to staple foods (milk, egg, wheat, soy, and fish). Conclusion: Wheat sensitization caused by cross-reactivity but also by sensitization to wheat-specific allergens was common in the grass-allergic children and also associated with allergy to staple foods other than wheat. The results indicate the presence of a subgroup of pollinosis patients with simultaneous sensitization to wheat and food allergy not only caused by cross-reactions.

Misleading Allergens in the Diagnosis of Latex Allergy: Profilin and Cross-Reactive Carbohydrate Determinants

Background: It has been suggested that latex-specific IgE analysis may lead to false-positive results, especially in patients with pollen allergy. In the present study, the reasons underlying clinically irrelevant latex-specific IgE positivity were investigated. Methods: Thirty patients with latex allergy (group 1), 89 patients sensitised to aeroallergens (group 2a), and 98 healthy individuals without allergy (group 2b) were enrolled. Participants from all 3 groups were subjected to skin prick tests with aeroallergens including latex, latex-specific IgE analysis (ImmunoCAP), and nasal provocation test with latex. All cases demonstrating positive latex-specific IgE also underwent specific IgE tests (ImmunoCAP) with latex profilin, birch pollen profilin, peach lipid transfer protein, and pineapple bromelain as cross-reactive carbohydrate determinants. Results: Comparison of the atopic and healthy control groups showed that the rate of positive latex-specific IgE was significantly higher in group 2a. Latex profilin-, birch pollen profilin-, and bromelain-specific IgE were remarkably higher in group 2a. Conclusion: False positivity to latex-specific IgE in ImmunoCAP analysis may be observed in approximately 19% of patients with pollen allergy. Profilins and bromelain are the main contributors to clinically irrelevant positive latex-specific IgE.

Antigenic cross-reactivity between Schistosoma mansoni and pollen allergens from the birch tree (Betula verrucosa) and Timothy grass (Phleum pratense): involvement of shared glycan epitopes and implications for the hygiene hypothesis

Previous studies have shown that schistosome infection can protect against allergic symptoms, but the underlying mechanisms are still not fully understood. Here we have shown that rabbit IgG antibodies raised against Schistosoma mansoni soluble egg antigens (SmSEA) are cross-reactive with a wide array of molecules in Timothy grass pollen (TGP) and birch tree pollen (BTP). Five of the cross-reactive pollen molecules (two from TGP and three from BTP) were selected randomly and identified by tandem mass spectrometric (TMS) analysis to be, respectively, the TGP allergens Phl p 1 and Phl p 5b, and BTP glutathione S-transferase (GST), and the BTP allergens Bet v 1 and Bet v 6.0102. Rabbit anti-SmSEA IgG antibodies that cross-reacted with each of the five allergens were found to be reactive with three major S. mansoni egg antigens, IPSE/alpha-1, omega-1 and kappa-5. Pairwise alignment of the amino acid sequences of each of the five TMS-identified pollen allergens with each of the three egg antigens revealed a low level of amino acid sequence identity. Further experiments indicated that the schistosome antigen/allergen cross-reactivity was mostly due to similar glycans present in helminths and plants, but not in mammals: so called cross-reactive carbohydrate determinants (CCDs). Previously, CCDs have been implicated in the cross-reactivity between many plants and invertebrates. Furthermore, pollen-induced anti-CCD IgGs have been found in sera of patients undergoing allergen-specific immunotherapy (SIT) and implicated in the treatment of the allergy. Thus, our finding provides not only possible explanations for the allergy-protective effect of helminth/schistosome infections as explained by the hygiene hypothesis, but also a potential starting point for improved SIT.

A preliminary study of serum IgE against cross-reactive carbohydrate determinants (CCD) in client-owned atopic dogs.

Cross-reactive carbohydrate determinants (CCD) are defined carbohydrate portions of glycoprotein cell surface molecules common to many plant and insect species. Mammalian species recognize CCD as foreign antigens and can mount humoral immune responses against them. Approximately 20-37% of grass and venom allergic people possess circulating IgE against CCD; these antibodies are generally considered clinically irrelevant. Anti-CCD IgE is, however, recognized as a cause of false positive, clinically incongruent serum allergen test results in people; this phenomenon has not been investigated in animals. To determine if anti-CCD IgE could be detected in sera of client-owned atopic dogs and how frequently it is found. Sera from 38 dogs with a clinical diagnosis of atopic dermatitis and prior serological evidence of IgE antibodies, defined as a positive result to at least one mite and pollen (of any type). Sera were analysed for IgE against CCD and environmental allergens with a commercially available multiplex enzyme-labelled allergen-specific IgE assay. Anti-CCD IgE was detected in nine of 38 (24%) of atopic dog sera. As with their human counterparts, all dogs with anti-CCD IgE had strong serological reactivity to grass pollens. Anti-CCD IgE can confound serological allergen testing in people; the same might be true in dogs. Further studies are warranted to investigate the clinical implications of anti-CCD IgE in dogs, including the potential for these antibodies to affect serum allergen-specific IgE assays used for clinical diagnosis, and whether they are relevant to clinical disease.

Component-resolved diagnostics to direct in venom immunotherapy: Important steps towards precision medicine.

Stings of Hymenoptera can induce IgE-mediated systemic and even fatal allergic reactions. Venom-specific immunotherapy (VIT) is the only disease-modifying and curative treatment of venom allergy. However, choosing the correct venom for VIT represents a necessary prerequisite for efficient protection against further anaphylactic sting reactions after VIT. In the past, therapeutic decisions based on the measurement of specific IgE (sIgE) levels to whole venom extracts were not always straightforward, especially when the patient was not able to identify the culprit insect. In the last years, the increasing knowledge about the molecular structure and relevance of important venom allergens and their availability as recombinant allergens, devoid of cross-reactive carbohydrate determinants, resulted in the development of an advanced component-resolved diagnostics (CRD) approach in venom allergy. Already to date, CRD has increased the sensitivity of sIgE detection and enabled the discrimination between primary sensitization and cross-reactivity, particularly in patients with sensitization to both honeybee and vespid venom. Hence, CRD in many patients improves the selection of the appropriate immunotherapeutic intervention. Moreover, the detailed knowledge about sensitization profiles on a molecular level might open new options to identify patients who are at increased risk of side-effects or not to respond to immunotherapy. Therefore, increasing potential of CRD becomes evident, to direct therapeutic decisions in a personalized and patient-tailored manner. Reviewed here are the state of the art options, recent developments and future perspectives of CRD of Hymenoptera venom allergy.

Venoms of Neotropical wasps lack cross-reactive carbohydrate determinants enabling reliable protein-based specific IgE determination

Venoms of Neotropical wasps lack cross-reactive carbohydrate determinants enabling reliable protein-based specific IgE determination