Heterogeneity in allergy to mollusks: a clinical-immunological study in a population from the North of Spain

ABSTRACT

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 crossreactivity. 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 (AU)

RESUMEN

Introducción: La alergia a moluscos ha sido menos estudiada y está peor caracterizada que la alergia a crustáceos. Objetivo: Describir las características clínicas de pacientes alérgicos a moluscos, identificar los alérgenos responsables y estudiar la reactividad cruzada entre ellos. Métodos: Estudio multicéntrico, prospectivo. Se incluyen 45 pacientes con alergia a moluscos, definida como una clínica sugestiva y prueba cutánea positiva con el molusco sospechoso. Se identificaron las bandas alergénicas mediante SDS-PAGE e inmunodetección. Las proteínas responsables se identificaron utilizando espectrometría de masas. Se realizaron ensayos de inhibición de ELISA entre moluscos, ácaros y crustáceos. Resultados: Veinticinco (55%) de los pacientes eran alérgicos a cefalópodos, 14 (31%) a bivalvos y 11 (24%) a gasterópodos. La lapa resultó ser la tercera causa de alergia (15% de los casos). Los síntomas fueron sistémicos en 31 pacientes (69%), diez (22%) tuvieron síndrome de alergia oral y siete (15%) urticaria de contacto. La mayoría de las bandas alergénicas estaban entre 27 y 47 kDa. Los ensayos de inhibición de ELISA mostraron un alto grado de inhibición de cefalópodos y bivalvos por parte de moluscos, ácaros y crustáceos. Mediante espectometría de masas se identificaron tropomiosina, actina y miosina como los alérgenos mayoritarios. Conclusiones: Los moluscos que con más frecuencia provocan reacciones alérgicas son los cefalópodos, especialmente el calamar. Llama la atención la elevada frecuencia de alergia a la lapa, a pesar de su bajo consumo. También hay que resaltar la heterogeneidad observada, por ejemplo en los gasterópodos. La tropomiosina parece ser responsable de la elevada reactividad cruzada encontrada entre moluscos, ácaros y crustáceos. Se han identificado tres nuevos alérgenos en los moluscos actina, enolasa y putative C1q domain-containing protein (AU)