A population-based questionnaire survey on the prevalence of peanut, tree nut, and shellfish allergy in 2 Asian populations.

BACKGROUND: There has been a substantial increase in the prevalence of peanut and tree nut allergy in Western populations in the last 2 decades. However, there is an impression that peanut and tree nut allergy is relatively uncommon in Asia. OBJECTIVE: To evaluate the prevalence of peanut, tree nut, and shellfish allergy in schoolchildren in 2 Asian countries (Singapore and Philippines). METHODS: A structured written questionnaire was administered to local and expatriate Singapore (4-6 and 14-16 years old) and Philippine (14-16 years old) schoolchildren. RESULTS: A total of 25,692 schoolchildren responded to the survey (response rate, 74.2%). Of these, 23,425 responses fell within the study protocol's 4 to 6 and 14 to 16 year age groups and were included in the analysis. The prevalence of convincing peanut and tree nut allergy were similar in both local Singapore (4-6 years, 0.64%, 0.28%; 14-16 years, 0.47%, 0.3%, respectively) and Philippine (14-16, 0.43%, 0.33%, respectively) schoolchildren, but was higher in the Singapore expatriates (4-6 years, 1.29%, 1.12%; 14-16 years, both 1.21%, respectively; 4-6 years, expatriates vs local Singaporeans: peanut, P = .019; tree nut, P = .0017; 14-16 years, P > .05). Conversely, shellfish allergy was more common in the local Singapore (4-6 years, 1.19%; 14-16 years, 5.23%) and Philippine (14-16 years, 5.12%) schoolchildren compared with expatriate children (4-6 years, 0.55%; 14-16 years, 0.96%; P < .001). When data were pooled, respondents born in Western countries were at higher risk of peanut (adjusted odds ratios [95% CIs]: 4-6 years, 3.47 [1.35-8.93]; 14-16 years, 5.56 [1.74-17.76]) and tree nut allergy (adjusted odds ratios [95% CIs]: 4-6 years, 10.40 [1.61-67.36]; 14-16 years, 3.53 [1.00-12.43]) compared with those born in Asia. CONCLUSION: This study substantiates the notion that peanut and tree nut allergy is relatively low in Asian children, and instead shellfish allergy predominates. Environmental factors that are yet to be defined are likely to contribute to these differences.

Roles of structure and structural dynamics in the antibody recognition of the allergen proteins: an NMR study on Blomia tropicalis major allergen.

Blo t 5 is the major allergen from Blomia tropicalis mites and shows strong IgE reactivity with up to 90% of asthmatic and rhinitis patients' sera. The NMR solution structure of Blo t 5 comprises three long alpha helices, forming a coiled-coil, triple-helical bundle with a left-handed twist. TROSY-NMR experiments were used to study Blo t 5 interaction with the Fab' of a specific monoclonal antibody, mAb 4A7. The mAb epitope comprises two closely spaced surfaces, I and II, connected by a sharp turn and bearing critical residues Asn46 and Lys47 on one surface, and Lys54 and Arg57 on the other. This discontinuous epitope overlaps with the human IgE epitope(s) of Blo t 5. Epitope surface II is further predicted to undergo conformational exchange in the millisecond to microsecond range. The results presented are critical for the design of a hypoallergenic Blo t 5 for efficacious immunotherapy of allergic diseases.

Parvalbumin--the major tropical fish allergen.

Fish allergy is common in countries where consumption is high. Asian nations are amongst the world's largest consumers of fish but the allergen profiles of tropical fish are unknown. This study sought to evaluate the allergenicity of four commonly consumed tropical fish, the threadfin (Polynemus indicus), Indian anchovy (Stolephorus indicus), pomfret (Pampus chinensis) and tengirri (Scomberomorus guttatus). Immunoglobulin E (IgE) cross-reactivity with parvalbumin of cod fish (Gad c 1), the major fish allergen, was also studied. Detection of tropical fish and cod specific-IgE was performed by UniCap assay, and skin prick tests were also carried out. The IgE-binding components of tropical fish were identified using IgE immunoblot techniques, and cross-reactivity with Gad c 1 was assessed by ELISA inhibition and IgE immunoblot inhibition. Clinically, nine of 10 patients studied were allergic to multiple fish. All patients exhibited detectable specific-IgE to cod fish (10 of 10 skin prick test positive, eight of 10 UniCap assay positive) despite lack of previous exposure. The major allergen of the four tropical fish was the 12-kDa parvalbumin. IgE cross-reactivity of these allergens to Gad c 1 was observed to be moderate to high in the tropical fish studied. Parvalbumins are the major allergens in commonly consumed tropical fish. They are cross-reactive with each other as well as with Gad c 1. Commercial tests for cod fish appear to be sufficient for the detection of tropical fish specific-IgE.

The Blomia tropicalis allergens.

Blomia tropicalis allergens are the most important mite allergens in tropical regions. Most of them only have 30-40% sequence identity with their Dermatophagoides counterparts and they share low IgE cross reactivity and exhibit different immunobiology. Unlike the pyroglyphid counterparts, Blo t 5 is the major allergen whereas Blo t 1 only has modest allergenicity.

Molecular cloning of Blomia tropicalis allergens--a major source of dust mite allergens in the tropics and subtropics.

Allergic asthma, rhinitis, rhinoconjunctivitis and atopic dermatitis are the most common allergic disorders that are caused by the house dust mite (HDM). Beside pyroglyphid mites, the clinical importance of non-pyroglyphid mites has also been increasingly recognized in the recent years. Blomia tropicalis is the most important and ubiquitous mite species in tropical and subtropical regions of the world. Well-standardized and characterized allergens are essential for the diagnosis and therapy of house dust mite allergy as well as for the study of the pathophysiology of allergic disease. With the introduction of molecular biology, a number of house dust mite allergens were obtained by cloning the genes encoding the allergens. To date, seven allergens from Blomia tropicalis have been identified and characterized. Among these, Blo t 5, with unknown function, is the major allergen of Blomia tropicalis, with up to 92% of allergic patients sensitized to it. Native Blo t 5 has been purified and shown to consist of multiple isoforms. With advancing knowledge of these specific allergens, it is anticipated that targeted, effective, diagnostic, efficacious and safe therapeutic modalities would be developed.

Identification of the major allergenic components in Blomia tropicalis and the relevance of the specific IgE in asthmatic patients.

BACKGROUND: Blomia tropicalis has been reported to be a clinically important allergen in house dust. High prevalence of sensitization to B. tropicalis has been noted in asthmatic patients in Taiwan; however, the allergenic components and its impact on asthmatic patients remain to be clarified. OBJECTIVE: To analyze the prevalence of IgE against B. tropicalis and each allergenic component in asthmatic patients. METHODS: A series of recombinant allergenic components were used for skin tests. The B. tropicalis specific IgE in the serum were measured using the Pharmacia CAP System and immunoblot analysis. RESULTS: A total of 131 patients were included in this study: 44% of these 131 patients were allergic to B. tropicalis, 43% of the 80 B. tropicalis-sensitive patients were allergic to Blo t 5, and 75% of the 65 Blo t 5-sensitive patients were allergic to Blo t 5 fragment 3 (Blo t 5 70-117). The sera IgE binding activity to B. tropicalis was repeatedly tested after Dermatophagoides pteronyssinus absorption, and results showed that most patients were concurrently sensitized to D. pteronyssinus and B. tropicalis. In addition, in 2 (18%) of 11 patients, the B. tropicalis sensitization was caused by the cross-reactivity of D. pteronyssinus. CONCLUSION: A high prevalence of B. tropicalis sensitization was detected in our asthmatic patients, and most of them were concurrently sensitized to D. pteronyssinus and B. tropicalis. The major allergenic component and its IgE binding fragments in Blo t 5 have been identified. These allergenic components can be used for the allergenic determination in B. tropicalis and for further immunotherapy.