Seafood hypersensitivity in mite sensitized individuals: is tropomyosin the only responsible allergen?

Fractional exhaled nitric oxide (FeNO) and respiratory symptoms in junior high school students in Penang, Malaysia: the role of household exposure

We studied associations between fractional exhaled nitric oxide (FeNO), health and household exposure among school children (N = 348) in Penang, Malaysia. Multiple logistic regression and linear mixed models were applied. Overall, 46.0% had elevated FeNO (>20 ppb) and 10.6% diagnosed asthma. Male gender (p = 0.002), parental asthma or allergy (p = 0.047), cat allergy (p = 0.009) and seafood allergy (p < 0.001), diagnosed asthma (p = 0.001), wheeze (p = 0.001), ocular symptoms (p = 0.001), rhinitis (p = 0.002) and respiratory infections (p = 0.004) were all associated with FeNO. Students exposed to ETS had lower FeNO (p = 0.05). Dampness and mould was associated with wheeze (p = 0.038), especially in wooden homes (interaction p = 0.042) and among students with elevated FeNO (interaction p = 0.024). Cat keeping increased rhinitis (p = 0.041) and respiratory infections (p = 0.008) and modified the dampness associations. In conclusion, FeNO can be associated with ocular and respiratory symptoms. Elevated FeNO, cat keeping and a wooden house can enhance the risk of wheeze when exposed to dampness and mould.

Anaphylaxis after Shrimp Intake in a European Pediatric Population: Role of Molecular Diagnostics and Implications for Novel Foods

(1) Background: Tropomyosin is a major cause of shellfish allergy and anaphylaxis triggered by food. It acts as a pan-allergen, inducing cross-reactivity in insects, dust mites, crustaceans, and mollusks. Our study investigates anaphylaxis in children with asthma or atopic diseases after consuming tropomyosin-containing food. (2) Methods: We analyzed the molecular sensitization profiles of pediatric patients at the University of Campania 'Luigi Vanvitelli' from 2017 to 2021, with conditions such as allergic rhinitis, asthma, atopic dermatitis, urticaria, and food allergies. (3) Results: Out of a total of 253 patients aged 1 to 18 years (167 males, 86 females), 21 patients (8.3%) experienced anaphylaxis after shrimp ingestion. All 21 (100%) were sensitized to various tropomyosins: Pen m 1 (100%), Der p 10 (90.5%), Ani s 3 (81%), and Bla g 7 (76.2%). Clinical symptoms included allergic asthma (76.2%), atopic dermatitis (61.9%), urticaria (38.1%), and allergic rhinitis (38.1%). (4) Conclusions: Crustaceans and mollusks are major allergens in Italy and Europe, requiring mandatory declaration on food labels. Italian pediatric patients demonstrated significant anaphylaxis after consuming shrimp, often accompanied by multiple atopic disorders such as asthma, rhinitis, and atopic dermatitis. Considering the cross-reactivity of tropomyosin among various invertebrates and the emergence of 'novel foods' containing insect flours in Europe, there is ongoing debate about introducing precautionary labeling for these products.

Murine model identifies tropomyosin as IgE cross-reactive protein between house dust mite and coho salmon that possibly contributes to the development of salmon allergy

Background

Recently, we have developed a method to identify IgE cross-reactive allergens. However, the mechanism by which IgE cross-reactive allergens cause food allergy is not yet fully understood how. In this study, we aimed to understand the underlying pathogenesis by identifying food allergens that cross-react with house dust mite allergens in a murine model.

Material and methods

Allergenic protein microarray analysis was conducted using serum from mice intraperitoneally injected with Dermatophagoides pteronyssinus (Der p) extract plus alum or alum alone as controls. Der p, Dermatophagoides farinae (Der f), coho salmon extract-sensitized and control mice were analyzed. Serum levels of IgE against Der p, Der f, coho salmon extract, protein fractions of coho salmon extract separated by ammonium sulfate precipitation and anion exchange chromatography, and recombinant coho salmon tropomyosin or actin were measured by an enzyme-linked immunosorbent assay. A murine model of cutaneous anaphylaxis or oral allergy syndrome (OAS) was established in Der p extract-sensitized mice stimulated with coho salmon extract, tropomyosin, or actin.

Results

Protein microarray analysis showed that coho salmon-derived proteins were highly bound to serum IgE in Der p extract-sensitized mice. Serum IgE from Der p or Der f extract-sensitized mice was bound to coho salmon extract, whereas serum IgE from coho salmon extract-sensitized mice was bound to Der p or Der f extract. Analysis of the murine model showed that cutaneous anaphylaxis and oral allergic reaction were evident in Der p extract-sensitized mice stimulated by coho salmon extract. Serum IgE from Der p or Der f extract-sensitized mice was bound strongly to protein fractions separated by anion exchange chromatography of coho salmon proteins precipitated with 50% ammonium sulfate, which massively contained the approximately 38 kDa protein. We found that serum IgE from Der p extract-sensitized mice was bound to recombinant coho salmon tropomyosin. Der p extract-sensitized mice exhibited cutaneous anaphylaxis in response to coho salmon tropomyosin.

Conclusion

Our results showed IgE cross-reactivity of tropomyosin between Dermatophagoides and coho salmon which illustrates salmon allergy following sensitization with the house dust mite Dermatophagoides. Our method for identifying IgE cross-reactive allergens will help understand the underlying mechanisms of food allergies.

IgE Mediated Shellfish Allergy in Children-A Review

Shellfish is a leading cause of food allergy and anaphylaxis worldwide. Recent advances in molecular characterization have led to a better understanding of the allergen profile. High sequence homology between shellfish species and between shellfish and house dust mites leads to a high serological cross-reactivity, which does not accurately correlate with clinical cross-reactions. Clinical manifestations are immediate and the predominance of perioral symptoms is a typical feature of shellfish allergy. Diagnosis, as for other food allergies, is based on SPTs and specific IgE, while the gold standard is DBPCFC. Cross-reactivity between shellfish is common and therefore, it is mandatory to avoid all shellfish. New immunotherapeutic strategies based on hypoallergens and other innovative approaches represent the new frontiers for desensitization.

Evaluation of Der p 10 in a Cohort of European Children: Role of Molecular Diagnostics and Clinical Features

Background

Allergy toward the dust mite is steadily increasing on the European continent. This sensitization may be a risk factor for developing sensitization to other mite molecules such as tropomyosin Der p 10. This molecule often correlates with food allergy and the risk of anaphylaxis after ingesting mollusks and shrimps.

Materials and Methods

We analyzed the sensitization profiles by ImmunoCAP ISAC of pediatric patients from 2017 to 2021. The patients under investigation were being followed for atopic disorders such as allergic asthma and food allergies. The study aimed to analyze the prevalence of sensitization toward Der p 10 in our pediatric population and assess the related clinical symptoms and reactions after ingestion of foods containing tropomyosins.

Results

This study included 253 patients; 53% were sensitized toward Der p 1 and Der p 2; 10.4% were also sensitized to Der p 10. Assessing patients sensitized to Der p 1 or Der p 2, and Der p 10, we observed that 78.6% were affected by asthma (p < 0.005) and had a history of prior anaphylaxis after ingestion of shrimp or shellfish (p < 0.0001).

Conclusion

The component-resolved diagnosis gave us a deeper understanding of patients' molecular sensitization profiles. Our study showed that a fair proportion of children sensitive to Der p 1 or Der p 2 are also sensitive to Der p 10. However, many patients sensitized to all three molecules had a high risk of asthma and anaphylaxis. Therefore, the assessment of Der p 10 sensitization should be considered in atopic patients with sensitization to Der p 1 and Der p 2 to avoid encountering possible adverse reactions after ingesting foods containing tropomyosins.

In Silico Prediction of Cross-Reactive Epitopes of Tropomyosin from Shrimp and Other Arthropods Involved in Allergy

Tropomyosin in shellfish is considered a major cross-reactive allergen in house dust mites and cockroaches; however, the specific epitopes have not been elucidated. Therefore, this study aimed to identify the consensus antigenic determinant among shrimp, house dust mites, and cockroaches using in silico methods. The protein sequences of tropomyosin, including Der f 10, Mac r 1, Pen a 1, Pen m 1, Per a 7, and Bla g 7, were retrieved from the UniProt database. The 3D structures were derived from the AlphaFold or modeled using the Robetta. The determination of linear epitopes was performed by AlgPRED and BepiPRED for B cell epitope, and NetMHCIIpan and NetMHCII for T cell epitope, while Ellipro was used to evaluate conformational epitopes. Fourteen peptides were discovered as the consensus linear B cell epitopes, while seventeen peptides were identified as linear T cell epitopes specific to high-frequency HLA-DR and HLA-DQ alleles. The conformational determination of B cell epitopes provided nine peptides, in which residues 209, 212, 255–256, and 258–259 were found in both linear B cell and linear T cell epitope analysis. This data could be utilized for further in vitro study and may contribute to immunotherapy for allergic diseases associated with tropomyosin.

Clinical utility of immunological methods based on the singleplex and multiplex ImmunoCap systems for diagnosis of shrimp allergy

BACKGROUND

Levels of specific IgE (sIgE) against allergen components can be assessed using multiplex assays or with highly sensitive, quantitative methods. The aim of this study was to compare the sensitivity and specificity of different immunological methods for diagnosis of shrimp allergy.

METHODS

Twenty patients with positive skin prick tests for frozen tiger shrimp were selected for further examination. Blood samples were taken to assess concentrations of sIgE against the house dust mites Dermatophagoides pteronyssinus and D. farinae, shrimp allergen extract, allergen components Der p 1, Der p 2 and Pan a 1 (ImmunoCap), and the ImmunoCap ISAC 112 panel.

RESULTS

All patients had elevated levels of sIgE against shrimp and D pteronyssinus. Eight patients were sensitized to Pen m 1, three patients were sensitized to Pen m 2, and two patients were sensitized to Pen m 4 (ISAC). ImmunoCap ISAC detected shrimp sensitization in 50% of patients. There was a strong correlation between concentrations of sIgE against Pen m1 and Der p 10 detected by ImmunoCap.

CONCLUSIONS

The singleplex ImmunoCap system remains the reference diagnostic method, but in the case of shrimp allergy ImmunoCap ISAC provided better insight into patient allergen profiles.

Shrimp sensitization in house dust mite allergic patients

Shrimp tropomyosin has a similar structure to house dust mite (HDM) tropomyosin. In this research, 232 adult patients with symptoms of persistent allergic rhinitis were randomly selected. In the group, 59% were sensitized to Dermatophagoides pteronyssinus and 57.8% to Dermatophagoides farinae. In total, 128 (55.2%) patients were sensitized to both HDM species and 143 (61.6%) to at least one. Slightly over a quarter (25.4%) of patients were sensitized to shrimp. Of the 35 shrimp-sensitized patients, the sensitization to Der p 10 and Pen a 1 was found in 11 cases (31.4%). There was a strong correlation between IgE Pen a 1 and IgE Der p 10 concentrations. The results indicate that there are other allergens responsible for a high incidence of shrimp sensitization in HDM-sensitized patients. A high convergence of Der p 10 and Pen a 1 levels may indicate that the determination of just one of the above is reasonable.

Analysis of allergen profile in patients sensitized to canine allergen and potential Can f 5 cross-reactivity with human PSA

Can f 5 allergy and possible cross-reactivity with human semen in which there are significant amounts of prostate-specific antigen (PSA) are particularly interesting aspects of allergy to dog. The objective of the study was to confirm cross-reactivity between human PSA and Can f 5 in a study of canine sensitised women. A total of 100 women (aged 18-73, 41 on average) with a positive history of animal fur allergy or positive skin prick tests to canine allergens were selected. Levels of Immunoglobulin E (IgE) specific to Can f 1, Can f 2, Can f 3, Can f 5 were determined. Patients with increased concentration of sIgE Can f 5 were selected for further inhibition testing using polystyrene microplate ELISA test coated with human PSA. In the studied population, allergy to Can f 5 dominated (52.3% of patients with increased concentration of canine-specific IgE were allergic to this allergenic component). In all analyzed cases, the concentration of IgE Can f 5 decreased after incubation on the ELISA plate coated with human PSA. The minimum decrease in concentration was 10.44%, the maximum was 37.73%, the average decrease was 21.6%. No statistically significant influence of the presence or absence of allergenic sIgE Can f 5 in blood serum on the occurrence of symptoms after intercourse was found. The study confirmed the moderate ability of Can f 5 to cross-react with human PSA sIgE, which may be clinically significant in some women. At the same time, symptoms of an allergy to male semen do not constitute a typical clinical presentation of allergy to Can f 5.

Occupational allergic contact urticaria to tropomyosin from squid

A cook’s mate working in an Austrian restaurant reported acutely occurring urticarial skin lesions after processing and cooking squid. The prick-to-prick test with squid showed a ++ positive urticarial reaction. Elevated specific IgE antibody levels to squid, shrimp, and house dust mites as well as to tropomyosin from shrimp and house dust mite could be detected in the ImmunoCAP. By means of immunoblot and ELISA, a reaction to squid extract as well as increased IgE antibody levels to squid and tropomyosin from squid could be detected. The patient was diagnosed with a clinically and occupationally relevant type I allergy to squid with cross-reaction to tropomyosin of other invertebrates and therefore recognized as an occupational disease.

Possible Role of Environmental Factors in the Development of Food Allergies

The development of food allergies is thought to involve multiple factors, and it is unclear which conveys the most risk regarding this process. Since food allergy is a chronic disease without a cure at this time, understanding its development could provide an avenue for preventive practices and development of a curative treatment. Both historical and current data implicate maternal factors, genetics, and environmental exposures as major risk factors in the development of food allergy. An immature gut of the infant has been hypothesized as a possible route of sensitization. Breastfeeding until at least 6 months of age has been shown to have protective factors for the newborn and may possibly improve gut permeability. Newer studies such as the LEAP and EAT investigations also looked at early exposure and prevention of food allergies; their long-term results are critical in understanding early introduction and tolerance. Cutaneous exposure, oral exposure, and food protein exposure in house dust with their relation to the food allergy course are also a path of interest. Current research has shown sensitization can occur through impaired skin such as those with eczema and a filaggrin mutation. Tropomyosin and alpha-gal also are related to the complicated immunomodulatory factors involved in food allergy and allergic response. Cross-reactivity with plant allergens, sensitization to house dust mite and cockroach, and lone star tick bites can also induce food allergens in children and adults. Together, these factors provide a cohesive beginning to understanding how food allergies can occur and can influence further investigation into prevention, treatment, and eventual cure of food allergies.

Improved diagnostic clarity in shrimp allergic non-dust-mite sensitized patients

BACKGROUND

Allergen specific immunoglobulin E (sIgE) levels predictive of shrimp allergy have not been identified, but these may be helpful in identifying patients at risk for shrimp-induced allergic reactions.

OBJECTIVE

This study sought to identify component resolved diagnostic tests useful for diagnosis of shrimp allergy in patients with or without house-dust mite (HDM) sensitization to the major allergen cysteine protease (Der p 1).

METHODS

Patients with positive skin-prick test (SPT) results and/or sIgE values were recruited. Shrimp allergy was classified by oral food challenge (OFC) or by a clear history of anaphylaxis after shrimp ingestion. Patients with shrimp allergy and patients who were tolerant were further classified based on HDM sensitivity (Der p 1 > 0.35 kUA/L). Testing for sIgE to total shrimp, and shrimp and HDM components was performed. The Fisher exact test, Wilcoxon sum rank test, and receiver operating characteristics analyses were used to compare sIgE levels in patients with allergy and patients who were tolerant.

RESULTS

Of 79 patients recruited, 12 patients with shrimp allergy (7 with positive OFC results and 5 with a history of anaphylaxis) and 18 patients who were shrimp tolerant were enrolled. Of the patients not HDM sensitized, sIgE levels to shrimp (10.5 kUA/L, p = 0.012) and Der p 10 (4.09 kUA/L, p = 0.035) were higher in patients with shrimp allergy. Shrimp sIgE of ≥3.55 kUA/L had 100% diagnostic sensitivity and 85.7% specificity (receiver operating characteristic 0.94 [0.81, 1.0] 95% CI) and Der p 10 sIgE levels of ≥3.98 kUA/L had a diagnostic sensitivity of 80% and specificity of 100% (receiver operating characteristic 0.86 [0.57, 1.0] 95% CI) for prediction of clinical reactivity.

CONCLUSION

HDM sensitization influences shrimp and HDM component sIgE levels and, consequently, their diagnostic accuracy in shrimp allergy. In our series, in the patients who were non-HDM sensitized, a shrimp sIgE level of >3.55 kUA/L showed 100% sensitivity and, Der p 10 sIgE of >3.98 kUA/L showed 100% specificity for the diagnosis of shrimp allergy. These levels may not be applicable to every patient and, therefore, may not obviate the need for OFC.

Seafood allergy: A comprehensive review of fish and shellfish allergens

Seafood refers to several distinct groups of edible aquatic animals including fish, crustacean, and mollusc. The two invertebrate groups of crustacean and mollusc are, for culinary reasons, often combined as shellfish but belong to two very different phyla. The evolutionary and taxonomic diversity of the various consumed seafood species poses a challenge in the identification and characterisation of the major and minor allergens critical for reliable diagnostics and therapeutic treatments. Many allergenic proteins are very different between these groups; however, some pan-allergens, including parvalbumin, tropomyosin and arginine kinase, seem to induce immunological and clinical cross-reactivity. This extensive review details the advances in the bio-molecular characterisation of 20 allergenic proteins within the three distinct seafood groups; fish, crustacean and molluscs. Furthermore, the structural and biochemical properties of the major allergens are described to highlight the immunological and subsequent clinical cross-reactivities. A comprehensive list of purified and recombinant allergens is provided, and the applications of component-resolved diagnostics and current therapeutic developments are discussed.

High rate of house dust mite sensitization in a shrimp allergic southern Ontario population

Background

Shrimp and house dust mite (HDM) allergies are common in Canadians. Often, both of these allergies occur in the same patient. This may be due to homology of tropomyosin or other potentially shared proteins. The aim of our study was to assess the frequency of house dust mite sensitization in a shrimp allergic Canadian population.

Methods

We undertook a retrospective chart review of shrimp allergic patients at an outpatient allergy clinic in Kitchener, Ontario, Canada. Our primary endpoint was to assess for presence of HDM sensitization in this population. Patients were categorized into approximate quartiles. We assessed the severity of the shrimp reactions, correlated shrimp skin test size to HDM skin test size, and measured the proportion of patients with atopic symptoms.

Results

We identified 95 shrimp allergic patients who were tested for house dust mite. 86 (90.5%) of these patients had a positive skin test to HDM. Patients with a shrimp skin test ≥5 mm were 5.31 times (95% CI, 1.55–18.14; p = 0.008) more likely to exhibit a dust mite skin test ≥5 mm than patients with a shrimp skin test <5 mm. The odds of a patient with a shrimp skin test between 10 and 18 mm having a larger HDM skin test were 3.93 times (95% CI 1.03–14.98, p = 0.045) the odds for a patient with a shrimp skin test size between 3 and 4 mm. We did not find a correlation between shrimp skin test size and shrimp reaction symptom grade (p = 0.301).

Conclusion

In our Canadian patients, we found a large majority of shrimp allergic patients to be sensitized to HDM. We found that patients with a large skin test to shrimp were more likely to have a large skin test to HDM compared to those patients with a small skin test to shrimp. We did not find a correlation between shrimp skin test size and shrimp reaction symptom severity. Most of these patients had symptoms of rhinitis and/or asthma that may have been caused by house dust mite allergy.

Food Allergy

Food allergy is receiving increased attention in recent years. Because there is currently no known cure for food allergy, avoiding the offending food is the best defense for sensitive individuals. Type I food allergy is mediated by food proteins, and thus, theoretically, any food protein is a potential allergen. Variability of an individual's immune system further complicates attempts to understand allergen-antibody interaction. In this article, we briefly review food allergy occurrence, prevalence, mechanisms, and detection. Efforts aimed at reducing/eliminating allergens through food processing are discussed. Future research needs are addressed.

High prevalence of Anisakis simplex hypersensitivity and allergy in Sicily, Italy

BACKGROUND

Anisakis simplex can elicit allergic reactions when ingested in raw or marinated fish. The prevalence of A simplex hypersensitivity and allergy in Sicily (Italy), an area where the consumption of raw or marinated fish is very common, has not been investigated thus far.

OBJECTIVE

To investigate the prevalence of A simplex sensitization and its clinical relevance in a large group of unselected patients.

METHODS

All consecutive patients referred to the authors' allergy clinic during a 22 month-period were included in the study, evaluated for sensitization to A simplex and other allergens depending on their clinical history, and investigated for allergic symptoms after the ingestion of raw or marinated fish.

RESULTS

Of 3,419 patients screened, 527 (15.4%) were sensitized to A simplex and 29 of these (5.5% of sensitized patients) had a history of A simplex allergy. Approximately 30% of patients had mono-sensitization to A simplex. Co-sensitization to house dust mites or molds yielded an odds ratio of 1.98 or 3.18, respectively, for allergy to A simplex.

CONCLUSION

A high prevalence of A simplex sensitization in a large proportion of patients with mono-sensitization was found, confirming that eating habits influence sensitization to this nematode. Allergic symptoms from A simplex ingestion in raw or marinated fish were quite frequent, with symptoms ranging from oral allergy syndrome to anaphylaxis. Patients sensitized to A simplex were more prone to have allergic symptoms when they had co-sensitization to house dust mites or molds, suggesting possible cross-reactive but clinically relevant allergens between these allergenic sources.

In vivo diagnosis with purified tropomyosin in mite and shellfish allergic patients

BACKGROUND

Tropomyosin is the most studied shellfish allergen and has been involved in cross-reactivity among different invertebrates (crustacean, mollusks, mites, insects, and nematodes).

OBJECTIVE

To determine the relevance of tropomyosin in mite- and shellfish-sensitized patients using tropomyosin skin testing.

METHODS

Patients were divided into 3 groups: group M included mite allergic patients (ie, individuals with respiratory symptoms and a positive result on skin prick testing [SPT] to house dust mites), group S included shellfish allergic patients (ie, individuals who reported symptoms with shellfish), and group MS included mite- and shellfish allergic patients (ie, individuals who simultaneously fulfilled the inclusion criteria for groups M and S). Tropomyosin was purified from shrimp, characterized, and used in SPT for diagnosis in the patient population.

RESULTS

Eight hundred fifty patients were included in the study: 790 (92.9%) in group M, 21 (2.5%) in group S, and 39 (4.6%) in group MS. Tropomyosin was purified from shrimp with a purity higher than 95%. Forty-two individuals tested positive to tropomyosin: the prevalence was 2.7% in group M, 28.6% in group S, and 38.5% in patients of group MS. Twenty-one (50%) of the tropomyosin-positive individuals had symptoms with shellfish, and 3 (14.3%) reported anaphylaxis.

CONCLUSION

The prevalence of tropomyosin was low in mite-sensitized patients (2.7 %) and high in shellfish allergic patients (28.6%). The higher prevalence of tropomyosin was found in patients sensitized to both mite and shellfish (38.5%). The selection of tropomyosin-sensitized patients by SPT might help in the choice of appropriate treatments or management for these patients.

Sensitization pattern of crustacean-allergic individuals can indicate allergy to molluscs

This study investigated the sensitization pattern of crustacean-allergic patients according to tolerance to molluscs. Thirty-one patients with anaphylaxis to crustaceans (14 with mollusc allergy and 17 with mollusc tolerance) were studied using skin prick tests (SPTs), specific IgEs (sIgEs) and SDS-PAGE immunoblotting. IgE-reactive shrimp proteins were identified by proteomic analyses. Patients with mollusc allergy presented more frequently SPTs positive to molluscs and higher sIgE titres in response to both molluscs and crustaceans. Shrimp-sIgE and rPen a1-sIgE values of 1.57 kUA /l and 4.38 kUA /l, respectively, showed positive likelihood ratios of 4.3 and 10.9 for the identification of mollusc allergy. Patients with mollusc allergy reacted more frequently to tropomyosin in immunoblots than did patients without it (93% vs 35%, respectively, P = 0.004). Reactivity to proteins other than tropomyosin (n = 14) was not different between the two groups. Among patients with crustacean anaphylaxis, patients with mollusc allergy and mollusc tolerance show a different pattern of sensitization, something that may help identify them.

Shellfish and House Dust Mite Allergies: Is the Link Tropomyosin?

Crustacean shellfish allergy is an important cause of food allergy and anaphylaxis in Asia. The major allergen in shellfish allergy is tropomyosin, a pan-allergen that is also found in house dust mites and cockroaches. Tropomyosins from house dust mites (HDMs) have a high sequence homology to shellfish tropomyosins, and cross-reactivity between HDM and shrimp tropomyosins has been demonstrated. Exposure to inhaled tropomyosins from house dust mites has been postulated to be the primary sensitizer for shellfish allergy, in a reaction analogous to the oral allergy (inhalant-food) syndrome. This notion is supported by indirect data from the effects of HDM immunotherapy on shellfish allergy, and strong correlations of shellfish and HDM sensitization. HDM immunotherapy has been reported to induce both shrimp allergy in non-allergic patients and shrimp tolerance in shrimp-allergic patients. Epidemiological surveys have also demonstrated a strong correlation between shellfish and HDM sensitization in both hospital-based and community-based studies. Unexposed populations have also been shown to develop sensitization-shellfish sensitization in orthodox Jews with no history of shellfish consumption was associated with HDM sensitization. Reciprocally, HDM sensitization in an Icelandic population living in a HDM-free environment was associated with shrimp sensitization. In vitro IgE inhibition studies on sera in shrimp-allergic Spanish patients indicate that mites are the primary sensitizer in shrimp-allergic patients living in humid and warm climates. Current data supports the hypothesis that tropomyosin is the link between HDM and shellfish allergies. The role of tropomyosin in HDM and shellfish allergies is a fertile field for investigation as it may provide novel immunotherapeutic strategies for shellfish allergy.

The development of a standardised diet history tool to support the diagnosis of food allergy

The disparity between reported and diagnosed food allergy makes robust diagnosis imperative. The allergy-focussed history is an important starting point, but published literature on its efficacy is sparse. Using a structured approach to connect symptoms, suspected foods and dietary intake, a multi-disciplinary task force of the European Academy of Allergy and Clinical Immunology developed paediatric and adult diet history tools. Both tools are divided into stages using traffic light labelling (red, amber and green). The red stage requires the practitioner to gather relevant information on symptoms, atopic history, food triggers, foods eaten and nutritional issues. The amber stage facilitates interpretation of the responses to the red-stage questions, thus enabling the practitioner to prepare to move forward. The final green stage provides a summary template and test algorithm to support continuation down the diagnostic pathway. These tools will provide a standardised, practical approach to support food allergy diagnosis, ensuring that all relevant information is captured and interpreted in a robust manner. Future work is required to validate their use in diverse age groups, disease entities and in different countries, in order to account for differences in health care systems, food availability and dietary norms.

Different sensitization to storage mites depending on the co-exposure to house dust mites

BACKGROUND

Co-sensitization to house dust mites (HDMs) and storage mites (SMs) is very frequent, although the clinical relevance is not well established.

OBJECTIVE

To describe the pattern of sensitization and immunologic characterization of patients with positive skin prick test reactions to HDMs and SMs in 4 areas of Spain, selected according to high exposure to HDMs and variable exposure to SMs.

METHODS

One hundred sixty-nine individuals with positive skin prick test reactions to HDMs and SMs were included. Specific IgE levels to different mite species and to Der p 1, Der p 2, and Der p 10 were determined. Immunoblots to Dermatophagoides pteronyssinus, Lepidoglyphus destructor, and Tyrophagus putrescentiae extracts were carried out, and allergograms were obtained. Results of different areas were compared.

RESULTS

A high rate of polysensitization to SMs was observed, although 12% of participants did not have specific IgE to any SM species. Sensitization to Dermatophagoides species, Der p 2, and L destructor were predominant, although significant differences were observed among areas depending on the grade of exposure to SMs. In areas with high exposure, the SM allergogram showed greater recognition of group 2 allergen.

CONCLUSION

Sensitization patterns to SMs in patients sensitized to HDMs and SMs differ depending on the exposure to SMs. Sensitization, mainly to L destructor, seems to exist in areas with high exposure, possibly with group 2 allergens mainly involved. However, in areas with low SM populations, sensitizations observed by skin prick testing appear to be related to HDM exposure.

New shrimp IgE-binding proteins involved in mite-seafood cross-reactivity

SCOPE

Shrimp is a seafood consumed worldwide and the main cause of severe allergenic reactions to crustaceans. Seafood allergy has been related to mite sensitization, mainly mediated by tropomyosin, but other proteins could be involved. The aim of the study was to identify new shrimp allergens implicated in mite-seafood cross-reactivity (CR) in two different climate populations: dry and humid climates.

METHODS AND RESULTS

Shrimp and mite IgE-binding profiles of patients from continental dry and humid climates were analyzed by immunoblotting, and the most frequently recognized Solenocera melantho shrimp proteins were identified by MS as α-actinin, β-actin, fructose biphosphate aldolase, arginine kinase, sarcoplasmic calcium-binding protein, and ubiquitin. Using inhibition immunoblot assays, we demonstrate that tropomyosin and ubiquitin were responsible for mite-seafood CR from both climates; but also α-actinin and arginine kinase are implicated in dry- and humid-climate populations, respectively. Reciprocal inhibition assays demonstrated that mites are the primary sensitizer in humid-climate, as shrimp is in continental dry-climate population.

CONCLUSION

Several new shrimp allergens have been identified and should be considered in the diagnosis and treatment of shrimp allergy and mite-seafood CR. Differences in mite-seafood CR were founded to be based on the climate.

Overview of component resolved diagnostics

Component-resolved diagnostics (CRD) utilize purified native or recombinant allergens to detect IgE sensitivity to individual allergen molecules and have become of growing importance in clinical investigation of IgE-mediated allergies. This overview updates current developments of CRD, including multiarray test systems. Cross-reactions between allergens of known allergen families (i.e. to Bet v 1 homologues) are emphasised. In pollinosis as well as in allergy to hymenoptera venoms or to food, CRD allows to some extent discrimination between clinically significant and irrelevant sIgE results and the establishing of sensitisation patterns with particular prognostic outcomes (i.e. sensitisations to storage proteins which correlate with clinically severe reactions in peanut allergy). Further promising improvements in diagnostics are expected from additional, not yet commercially available, recombinant allergen diagnostics identifying particular molecules of risk. Overall, CRD may decrease the need for provocation testing and may also improve the specificity of allergen-specific immunotherapy.

Clinical and immunological changes of immunotherapy in patients with atopic dermatitis: randomized controlled trial

Background. Immunotherapy has proven to be an useful tool in the management of allergic respiratory diseases; however, little has been studied in atopic dermatitis. Objective. To evaluate the clinical and immunological impact of immunotherapy with mites allergen extracts in atopic dermatitis. Methods. Patients with atopic dermatitis were assigned with computer-generated randomization to either of the following groups: (a) controls received only topical treatment with steroids and/or tacrolimus and (b) actively treated patients received topical treatment plus immunotherapy. Levels of serum total IgE, mites-specific IgE and IgG4 were assessed at study start and after one year of immunotherapy. Results. 31 patients in the active group and 29 in the control group completed the study. Symptoms and medication scores were significantly reduced in the active group after six months. Three patients in the control group showed new sensitizations to mites, while 3 patients in the active group showed neosensitization to shrimp with negative oral food challenge. We observed significant increase of mites-specific IgG4 levels in active group. Conclusion. Specific allergen immunotherapy induced a tolerogenic IgG4 response to mite allergens associated with favorable clinical effects in atopic dermatitis patients.

Not all shellfish "allergy" is allergy!

The popularity of shellfish has been increasing worldwide, with a consequent increase in adverse reactions that can be allergic or toxic. The approximate prevalence of shellfish allergy is estimated at 0.5-2.5% of the general population, depending on degree of consumption by age and geographic regions. The manifestations of shellfish allergy vary widely, but it tends to be more severe than most other food allergens.

Tropomyosin is the major allergen and is responsible for cross-reactivity between members of the shellfish family, particularly among the crustacea. Newly described allergens and subtle differences in the structures of tropomyosin between different species of shellfish could account for the discrepancy between in vitro cross-antigenicity and clinical cross-allergenicity. The diagnosis requires a thorough medical history supported by skin testing or measurement of specific IgE level, and confirmed by appropriate oral challenge testing unless the reaction was life-threatening.

Management of shellfish allergy is basically strict elimination, which in highly allergic subjects may include avoidance of touching or smelling and the availability of self-administered epinephrine. Specific immunotherapy is not currently available and requires the development of safe and effective protocols.