[Cross reactions between Hymenoptera venoms from different families, genera and species]

Simultaneous reactivity with the venoms of different Hymenoptera is commonly seen in patients allergic to insect venoms. Strong, though individually variable, cross-reactivity occurs between the venoms of different Vespinae species (Vespula, Dolichovespula, Vespa). In Middle Europe, anaphylaxis after European hornet stings is nearly always due to cross-reactivity with Vespula venom. The identification of the primary venom in patients testing positive for Vespula and Polistes (paper wasps) is particularly important in Mediterranean areas. Component-resolved diagnosis with the marker allergens Ves v 5 and Pol d 5 may directly identify the causative venom in the majority of patients. There is substantial cross-reactivity between honeybee and bumblebee venom, sometimes causing allergic symptoms in patients allergic to honeybee venom after accidental bumblebee stings. However, subjects strongly exposed to bumblebees may show bumblebee-specific sensitization and require immunotherapy with bumblebee venom. More than half of all venom-allergic patients show double-positive test results to honeybee and vespid venoms. This may be due to true double sensitization or due to cross-reactivity between homologous allergens present in both venoms and sharing around 50 % sequence identity, i.e. hyaluronidases (Api m 2/Ves v 2), dipeptidyl peptidases (Api m 5/Ves v 3), and vitellogenins (Api m 12/Ves v 6). The clinical relevance of these cross-reactions is unknown. In up to 50 % the double-positivity is caused by clinically irrelevant IgE antibodies against CCDs. Many (though not all) patients with true double sensitization may be identified by means of the species-specific marker allergens Api m 1 and Ves v 1/5. Some Vespula venom-allergic patients may clinically cross-react to fire ant stings (Solenopsis), but otherwise allergen relationships with other ant species are not well studied.

A multicentre evaluation of the autograft procedure for young patients undergoing aortic valve replacement: update on the German Ross Registry†

OBJECTIVES

Conventional aortic valve replacement (AVR) in young, active patients represents a suboptimal solution in terms of long-term survival, durability and quality of life. The aim of the present work is to present an update on the multicentre experience with the pulmonary autograft procedure in young, adult patients.

METHODS

Between 1990-2013, 1779 adult patients (1339 males; 44.7 ± 11.6 years) underwent the pulmonary autograft procedure in 8 centres. All patients underwent prospective clinical and echocardiographic examinations annually. The mean follow-up was 8.3 ± 5.1 years (range 0-24.3 years) with a total cumulative follow-up of 14 288 years and 662 patients having a follow-up of at least 10 years.

RESULTS

The early (30-day) mortality rate was 1.1% (n = 19). Late (>30 day) survival of the adult population was comparable with the age- and gender-matched general population (observed deaths: 101, expected deaths: 91; P = 0.29). Freedom from autograft reoperation at 5, 10 and 15 years was 96.8, 94.7 and 86.7%, respectively, whereas freedom from homograft reoperation was 97.6, 95.5 and 92.3%, respectively. The overall freedom from reoperation was 94.9, 91.1 and 82.7%, respectively. Longitudinal modelling of functional valve performance revealed a low (<5%) probability of a patient being in higher autograft regurgitation grades throughout the first decade. Similarly, excellent homograft function was observed throughout the first 15 years.

CONCLUSION

The autograft principle results in postoperative long-term survival comparable with that of the age- and gender-matched general population and reoperation rates within the 1%/patient-year boundaries and should be considered in young, active patients who want to avoid the shortcomings of conventional prostheses.

IgE, IgG4 and IgA specific to Bet v 1-related food allergens do not predict oral allergy syndrome

BACKGROUND

Birch pollen-associated plant food allergy is caused by Bet v 1-specific IgE, but presence of cross-reactive IgE to related allergens does not predict food allergy. The role of other immunoglobulin isotypes in the birch pollen-plant food syndrome has not been investigated in detail.

METHODS

Bet v 1-sensitized birch pollen-allergic patients (n = 35) were diagnosed for food allergy by standardized interviews, skin prick tests, prick-to-prick tests and ImmunoCAP. Concentrations of allergen-specific IgE, IgG1, IgG4 and IgA to seven Bet v 1-related food allergens were determined by ELISA.

RESULTS

Bet v 1, Cor a 1, Mal d 1 and Pru p 1 bound IgE from all and IgG4 and IgA from the majority of sera. Immunoglobulins to Gly m 4, Vig r 1 and Api g 1.01 were detected in <65% of the sera. No significant correlation was observed between plant food allergy and increased or reduced levels of IgE, IgG1, IgG4 or IgA specific to most Bet v 1-related allergens. Api g 1-specific IgE was significantly (P = 0.01) elevated in celeriac-allergic compared with celeriac-tolerant patients. Likewise, frequencies of IgE (71% vs 15%; P = 0.01) and IgA (86% vs 38%; P = 0.04) binding to Api g 1.01 were increased.

CONCLUSION

Measurements of allergen-specific immunoglobulins are not suitable for diagnosing Bet v 1-mediated plant food allergy to hazelnut and Rosaceae fruits. In contrast, IgE and IgA to the distantly related allergen Api g 1 correlate with allergy to celeriac.

Marker allergens of weed pollen - basic considerations and diagnostic benefits in the clinical routine: Part 16 of the Series Molecular Allergology

The term weed is referring to plants used as culinary herbs and medicinal plants as well as ecologically adaptive and invasive segetal plants. In Europe, pollen of ragweed, mugwort, English plantain and pellitory are the main elicitors of weed pollen allergies. Presently, 35 weed pollen allergens have been identified. The most relevant belong to the protein families of pectate lyases, defensin-like proteins, non-specific lipid transfer proteins, and Ole e 1-like proteins. The sensitization frequency depends on geographic regions and might affect more than 50 % of pollen allergic patients in distinct regions. Due to overlapping flowering seasons, similar habitats, polysensitizations and cross-reactive (pan)-allergens, it is difficult to diagnose genuine weed pollen sensitization using pollen extracts. Marker allergens for component-resolved diagnostics are available for the important weed pollen. These are Amb a 1 (ragweed), Art v 1 (mugwort), Pla l 1 (English plantain) and Par j 2 (pellitory). Molecule-based approaches can be used to identify the primary sensitizer and thus enable selection of the appropriate weed pollen extracts for allergen immunotherapy.

Clinical characteristics and risk profile of patients with elevated baseline serum tryptase

BACKGROUND

The clinical relevance of elevated basal serum tryptase (eBST ≥ 11.4 ng/ml) often remains unclear.

METHODS

BST was assessed in 15,298 patients attending our outpatient clinic. Frequency and severity of anaphylaxis was compared in 900 patients with eBST and 900 patients with normal BST. The prevalence of eBST was evaluated in patients with drug reactions, urticaria, gastrointestinal symptoms or venom allergy. Mast cell-associated symptoms were recorded prospectively in 100 patients with eBST and 100 controls using a standardised questionnaire.

RESULTS

5.9% (n=900) of 15,298 patients had eBST ≥11.4 ng/ml (mean 20 ± 21 ng/ml, 11.4-390 ng/ml). In 47% of them BST was <15.0 and in 78% <20.0 ng/ml. In patients with normal BST (4.5 ± 2.1 ng/ml), mean levels increased continuously with age (0.28 ng/ml per decade; p<0.001). Fatigue, meteorism, muscle/bone ache, vertigo, tachycardia, flush, palpitations, diarrhoea and oedema were associated with eBST (p<0.05 to <0.0001) without significant differences between slightly (11.4-20 ng/ml) or strongly (>20 ng/ml) eBST. eBST was significantly associated with adverse reactions to drugs (34%), radio contrast media (15%) and insect stings (24%) (p<0.05). Anaphylaxis was more common in patients with eBST (21% vs. 14%, p<0.001). The relative role of insect stings, drugs and food as the most important triggers was similar in patients with elevated and normal BST. Severe reactions (grade 3/4) occurred most often in subjects with BST >20 ng/ml (BST <11.4 mg/ml: 2.8%; 11.5-20 ng/ml: 5.9%; >20 ng/ml: 12.4%).

CONCLUSIONS

In clinical practice it appears reasonable to assess BST, besides after anaphylactic reactions also in patients suffering repeatedly from vertigo, flush, tachycardia, palpitations, oedema and nausea. Even patients with slightly eBST have a higher risk of anaphylaxis and experience more severe reactions.

Chimeras of Bet v 1 and Api g 1 reveal heterogeneous IgE responses in patients with birch pollen allergy

BACKGROUND

Characterization of IgE-binding epitopes of allergens and determination of their patient-specific relevance is crucial for the diagnosis and treatment of allergy.

OBJECTIVE

We sought to assess the contribution of specific surface areas of the major birch pollen allergen Bet v 1.0101 to binding IgE of individual patients.

METHODS

Four distinct areas of Bet v 1 representing in total 81% of its surface were grafted onto the scaffold of its homolog, Api g 1.0101, to yield the chimeras Api-Bet-1 to Api-Bet-4. The chimeras were expressed in Escherichia coli and purified. IgE binding of 64 sera from Bet v 1-sensitized subjects with birch pollen allergy was determined by using direct ELISA. Specificity was assessed by means of inhibition ELISA.

RESULTS

rApi g 1.0101, Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4 bound IgE from 44%, 89%, 80%, 78%, and 48% of the patients, respectively. By comparing the amount of IgE binding to the chimeras and to rApi g 1.0101, 81%, 70%, 75%, and 45% of the patients showed significantly enhanced IgE binding to Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4, respectively. The minority (8%) of the sera revealed enhanced IgE binding exclusively to a single chimera, whereas 31% showed increased IgE binding to all 4 chimeras compared with rApi g 1.0101. The chimeras inhibited up to 70% of IgE binding to rBet v 1.0101, confirming the specific IgE recognition of the grafted regions.

CONCLUSION

The Bet v 1-specific IgE response is polyclonal, and epitopes are spread across the entire Bet v 1 surface. Furthermore, the IgE recognition profile of Bet v 1 is highly patient specific.

Determination of sIgE to rPhl p 1 is sufficient to diagnose grass pollen allergy

BACKGROUND

New diagnostic tools such as the basophil activation test (BAT) and component-resolved diagnosis (CRD) are promising for Hymenoptera venom or food allergy. A clear benefit for inhalant allergens has not yet been shown. Our aim was to compare new and established tests for grass pollen allergy.

METHODS

Forty-nine patients with grass pollen allergy and 47 controls were prospectively enrolled in the study. A symptom score was calculated for each patient. Conjunctival provocation tests (CPT), skin prick tests (SPT), BAT, and sIgE determination including CRD were performed. Sensitivity and specificity were compared and results were correlated with the symptom score.

RESULTS

Single determination of sIgE to rPhl p 1 showed the best balance between sensitivity (98%) and specificity (92%). Use of additional components, such as rPhl p 2 and 5, did not increase sensitivity. Generally, sensitivity of tests was high: SPT 100%, ISAC-112 100%, sIgE to timothy grass 98%, BAT 98%, ISAC-103 84%, and CPT 83%. Specificity ranged from 79% (SPT) to 96% (CPT). All test results and calculated values (e.g. ratio sIgE/tIgE) did not correlate with symptom severity. Asymptomatic sensitization to timothy grass in controls was rare in the CAP (11%) and predominantly due to Phl p 1 sensitization.

CONCLUSION

rPhl p 1 was sufficient to diagnose grass pollen allergy, and sIgE patterns were the same in symptomatically and asymptomatically sensitized subjects. The testing of multiple components was of minor importance, and no test correlated with symptom severity.

Inhibition of IgE binding to cross-reactive carbohydrate determinants enhances diagnostic selectivity

Background

Allergy diagnosis by determination of allergen-specific IgE is complicated by clinically irrelevant IgE, of which the most prominent example is IgE against cross-reactive carbohydrate determinants (CCDs) that occur on allergens from plants and insects. Therefore, CCDs cause numerous false-positive results. Inhibition of CCDs has been proposed as a remedy, but has not yet found its way into the routine diagnostic laboratory. We sought to provide a simple and affordable procedure to overcome the CCD problem.

Methods

Serum samples from allergic patients were analysed for allergen-specific IgEs by different commercial tests (from Mediwiss, Phadia and Siemens) with and without a semisynthetic CCD blocker with minimized potential for nonspecific interactions that was prepared from purified bromelain glycopeptides and human serum albumin.

Results

Twenty two per cent of about 6000 serum samples reacted with CCD reporter proteins. The incidence of anti-CCD IgE reached 35% in the teenage group. In patients with anti-CCD IgE, application of the CCD blocker led to a clear reduction in read-out values, often below the threshold level. A much better correlation between laboratory results and anamnesis and skin tests was achieved in many cases. The CCD blocker did not affect test results where CCDs were not involved.

Conclusion

Eliminating the effect of IgEs directed against CCDs by inhibition leads to a significant reduction in false-positive in vitro test results without lowering sensitivity towards relevant sensitizations. Application of the CCD blocker may be worthwhile wherever natural allergen extracts or components are used.

Vig r 6, the cytokinin-specific binding protein from mung bean (Vigna radiata) sprouts, cross-reacts with Bet v 1-related allergens and binds IgE from birch pollen allergic patients' sera

SCOPE

Birch pollen associated allergy to mung bean sprouts is caused by cross-reactivity between the birch pollen allergen Bet v 1 and the mung bean allergen Vig r 1. We aimed to determine the allergenicity of the cytokinin-specific binding protein from mung bean (Vig r 6), another allergen related to Bet v 1 with only 31% sequence identity.

METHODS AND RESULTS

Bet v 1, Gly m 4, Vig r 1, and Vig r 6 were produced in Escherichia coli. In an ELISA, 73 and 32% of Bet v 1-sensitized birch-allergic patients' sera (n = 60) showed IgE binding to Vig r 1 and Vig r 6, respectively. Of 19 patients who reported allergic reactions or had positive prick-to-prick tests to mung bean sprouts, 79% showed IgE binding to Vig r 1 and 63% showed IgE binding to Vig r 6. Bet v 1 completely inhibited IgE binding to both mung bean allergens. Vig r 6 showed partial cross-reactivity with Vig r 1 and activated basophils sensitized with mung bean allergic patients' sera.

CONCLUSION

We demonstrated IgE cross-reactivity despite low sequence identity between Vig r 6 and other Bet v 1-related allergens. Thus, IgE binding to Vig r 6 may contribute to birch pollinosis-associated mung bean sprout allergy.

Allergenic relevance of nonspecific lipid transfer proteins 2: Identification and characterization of Api g 6 from celery tuber as representative of a novel IgE-binding protein family

SCOPE

Apium graveolens represents a relevant food allergen source linked with severe systemic reactions. We sought to identify an IgE-binding nonspecific lipid transfer protein (nsLTP) in celery tuber.

METHODS AND RESULTS

A low molecular weight protein exclusively present in celery tuber was purified and designated Api g 6. The entire protein sequence was obtained by MS and classified as member of the nsLTP2 family. Api g 6 is monomeric in solution with a molecular mass of 6936 Da. The alpha-helical disulfide bond-stabilized structure confers tremendous thermal stability (Tm > 90°C) and high resistance to gastrointestinal digestion. Endolysosomal degradation demonstrated low susceptibility and the presence of a dominant peptide cluster at the C-terminus. Thirty-eight percent of A. graveolens allergic patients demonstrated IgE reactivity to purified natural Api g 6 in ELISA and heat treatment did only partially reduce its allergenic activity. No correlation in IgE binding and limited cross-reactivity was observed with Api g 2 and Art v 3, nsLTP1 from celery stalks and mugwort pollen.

CONCLUSION

Api g 6, a novel nsLTP2 from celery tuber represents the first well-characterized allergen in this protein family. Despite similar structural and physicochemical features as nsLTP1, immunological properties of Api g 6 are distinct which warrants its inclusion in molecule-based diagnosis of A. graveolens allergy.

Patient Age at the Ross Operation in Children Influences Aortic Root Dimensions and Aortic Regurgitation

Background:

The Ross operation provides the advantage of growth potential of the pulmonary autograft in the aortic position. However, development of autograft dilatation and regurgitation may occur. We sought to assess the progression of autograft diameters and aortic regurgitation (AR) with regard to patient age at the time of the Ross operation.

Methods:

Autograft echo dimensions from 48 children <16 years of age at the time of the Ross operation, who had follow-up echocardiograms at <20 years of age, were analyzed using hierarchical multilevel modeling. The z values of autograft dimensions were calculated according to the normal aortic dimensions. Mean follow-up was 5.1 ± 3.3 years. The mean age at the time of the Ross operation was 10.0 ± 4.3 years.

Results:

The mean z values of all patients showed a significant increase with follow-up time at the sinus (0.5 ± 0.1/year, P < .001) and the sinotubular junction (0.7 ± 0.2/year, P < .001) but not at the annulus (0.1 ± 0.1/year, P = .59). There was no significant difference in the z values of sinus and the sinotubular junction between younger and older children at implantation and with time. The initial annulus z value was significantly larger in younger children ( P < .0001), whereas the annual increase was significantly higher in older children ( P = .021). Age at operation has no impact on the initial AR grade ( P = .60). The AR tends to increase more quickly in older patients ( P = .040). Sinus and sinotubular junction dilate with time, regardless of patient age.

Conclusions:

Young children show larger initial annulus sizes than older children. However, annulus diameters tend to normalize in young children, whereas they increase in older children. Autograft regurgitation develops slowly, but significantly, and predominantly in older children. Stabilizing measures to prevent autograft root dilatation are warranted in adolescents, but they are not required in young children.