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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 2016; Vol. 27(4)
doi: 10.18176/jiaci.0137

Background: Allergy to mollusks has been the focus of fewer studies than crustaceans and is less well characterized.
Objective: To describe the clinical characteristics of patients allergic to mollusks, identifying the allergens responsible and to assess the cross-reactivity.
Methods: A prospective multicenter study including 45 patients with mollusk allergy, defined as a suggestive anamnesis and a positive skin test to the agent involved. Allergic fractions were identified using SDS-PAGE and immunoblotting. The proteins responsible were subsequently identified using mass spectrometry. ELISA inhibition studies were performed among mollusks, dust mites and crustaceans.
Results: Twenty-five (55%) of the patients were allergic to cephalopods, 14 (31%) to bivalves, and 11 (24%) to gastropods. Limpet represented the third cause of allergy, with 15% of cases. In 31 (69%) the manifestation was systemic, 10 (22%) exhibited oral allergy syndrome and 7 contact urticaria (15%).
The majority of the major allergens were found between 27 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 most frequently mollusks triggering allergic symptoms. It is striking the high occurrence of allergy to limpets in contrast with their low consumption. It is worth highlight 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: actin, enolase and a putative C1q domain-containing protein.

Key words: Mollusk, Allergy, Allergens.