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Heterogeneity in Allergy to Mollusks: A Clinical-Immunological Study in a Population From the North of Spain

Azofra J1, Echechipía S2, Irazábal B3, Muñoz D4, Bernedo N4, García BE2, Gastaminza G5, Goikoetxea MªJ5, Joral A6, Lasa E6, Gamboa P7, Díaz C1, Beristain A1, Quiñones D1, Bernaola G8, Echenagusia MA9, Liarte I3, García E7, Cuesta J10, Martínez MªD3, Velasco M4, Longo N4, Pastor-Vargas C11

1Sección de Alergia, Área de Gestión del Pulmón, Hospital Universitario Central de Asturias, Oviedo, Spain
2Servicio de Alergia, Complejo Hospitalario de Navarra, Pamplona, Spain
3Servicio de Alergia, Hospital de Cruces, Bilbao, Spain
4Servicio de Alergia, Hospital Universitario de Araba, Vitoria, Spain
5Departamento de Alergia, Clínica Universidad de Navarra, Pamplona, Spain
6Servicio de Alergia, Hospital Donostia, San Sebastián, Spain
7Servicio de Alergia, Hospital de Basurto, Bilbao, Spain
8Servicio de Alergia, Hospital de Galdácano, Bilbao, Spain
9Servicio de Alergia, Hospital de Mendaro, Guipúzcoa, Spain
10Departamento de Alergia, Fundación Jiménez Díaz, Madrid, Spain
11Departamento de Inmunología, IIS Fundación Jiménez Díaz, UAM, Madrid, Spain

J Investig Allergol Clin Immunol 2017; Vol 27(4) : 252-260
doi: 10.18176/jiaci.0137

Background: Allergy to mollusks has been the focus of fewer studies than allergy to crustaceans. Furthermore, allergy to mollusks is less well characterized.
Objectives: To describe the clinical characteristics of mollusk-allergic patients, to identify the responsible allergens, and to assess cross-reactivity.
Methods: We performed a prospective multicenter study including 45 patients with mollusk allergy, which was diagnosed based on a suggestive clinical history and a positive skin test result with the agent involved. Fractions were identified using SDS-PAGE and immunoblotting. The proteins responsible were subsequently identified using mass spectrometry. ELISA inhibition studies were performed with mollusks, dust mites, and crustaceans.
Results: We found that 25 patients (55%) were allergic to cephalopods, 14 (31%) to bivalves, and 11 (24%) to gastropods. Limpet was the third most frequent cause of allergy (15% of cases). In 31 patients (69%), the manifestation was systemic; 10 (22%) exhibited oral allergy syndrome, and 7 (15%) experienced contact urticaria. Most major allergens were found between 27 kDa and 47 kDa. ELISA inhibition assays revealed a high degree of inhibition of cephalopods and bivalves from all the groups of mollusks, mites, and crustaceans. Mass spectrometry identified tropomyosin, actin, and myosin as the major allergens.
Conclusions: Cephalopods, especially squid, are the mollusks that most frequently trigger allergic symptoms. The very frequent occurrence of allergy to limpets is striking, given their low consumption in our area. It is worth highlighting the heterogeneity observed, exemplified by the gastropods. Tropomyosin appears to be responsible for the high cross-reactivity found between mollusks, mites, and crustaceans. Three new mollusk allergens were also identified, namely, actin, enolase, and a putative C1q domain–containing protein.

Key words: Mollusk, Allergy, Allergens