Shrimp allergy: analysis of commercially available extracts for in vivo diagnosis

Background: Skin prick testing (SPT) with commercial extracts is the first step in the diagnosis of shrimp allergy, although its clinical efficiency is unknown. Objective: To analyze the clinical usefulness of all commercial crustacean extracts available for SPT in Italy. Methods: We performed a multicenter study of 157 shrimp-allergic patients who underwent SPT with 5 commercial crustacean extracts and with house dust mite (HDM) extract. Commercial extracts were analyzed using SDS-PAGE and compared with a freshly prepared in-house shrimp extract. IgE to Pen a 1/Pen m 1, Pen m 2, and Pen m 4 was determined, and immunoblot analysis was performed on a large number of sera. Results: The skin reactions caused by commercial crustacean extracts were extremely heterogeneous, resulting in 32 clinical profiles, with marked differences in protein content and missing proteins at molecular weights corresponding to those of major shrimp allergens. Only strong Pen a 1/Pen m 1 reactors reacted to both HDM and all 5 commercial extracts in SPT. Most patients, including those who were tropomyosin-negative, reacted to HDM. Patients reacted to a large and variable array of proteins, and IgE reactivity was common at high molecular weights (>50 kDa). Conclusions: The in vivo diagnosis of shrimp allergy must continue to be based on SPT with fresh material. Shrimp-allergic patients frequently react to a number of ill-defined high-molecular-weight allergens, thus leaving currently available materials for componentresolved diagnosis largely insufficient. Mites and crustaceans probably share several allergens other than tropomyosin (AU)

Introducción: Las pruebas cutáneas con extractos comerciales representan el primer paso en el diagnóstico de alergia a gamba, si bien, su eficacia clínica no está bien definida. Objetivos: El objetivo de este estudio fue analizar la utilidad clínica de todos los extractos comerciales disponibles en Italia frente a crustáceos en pruebas cutáneas. Métodos: En un estudio multicéntrico, se incluyeron 157 pacientes alérgicos a gamba a los que se realizaron pruebas cutáneas con cinco extractos comerciales de crustáceos y con ácaros del polvo doméstico. Los extractos comerciales fueron analizados mediante SDS-PAGE y comparados con un extracto de gamba preparado en fresco. Se determinó IgE frente a Pen a 1/Pen m 1; Pen m 2, y Pen m 4; y el análisis mediante inmunoblotting se realizó en un amplio número de sueros. Resultados: Los extractos de gamba comercializados dieron lugar a reacciones cutáneas muy poco homogéneas en 32 perfiles clínicos diferentes; así mismo, mostraron grandes diferencias en contenido proteico y, en algunos casos, a falta de proteína a pesos moleculares correspondientes a alérgenos mayoritarios de gamba. Únicamente los reactores más fuertes a Pen a1 /Pen m 1 reaccionaron tanto a ácaros del polvo de casa como a los cinco extractos comerciales en pruebas cutáneas. La mayoría de los pacientes, incluyendo los negativos a tropomiosina, reaccionaron a los ácaros del polvo. Los pacientes reaccionaron a un amplio y variable array de proteínas y se detectó con frecuencia reactividad de IgE en pesos moleculares altos (>50 kDa). Conclusiones: El diagnóstico in vivo de alergia a gamba todavía debe estar basado en pruebas cutáneas prick con producto fresco. Los pacientes alérgicos a gamba a menudo reaccionan a un número de alérgenos de peso molecular alto poco definido, lo que hace que las moléculas disponibles hoy en día para el diagnóstico por componentes sean muy insuficiente. Ácaros y crustáceos probablemente comparten varios alérgenos además de la tropiomiosina (AU)

Clinical manifestations, co-sensitizations, and immunoblotting profiles of buckwheat-allergic patients.

BACKGROUND: Buckwheat allergy is a rare food allergy in Europe and North America, whereas it is often described and studied in Asia. The aim of this study was to describe a series of patients with proven buckwheat allergy evaluated in an Italian allergy clinic. Co-sensitization to other food and inhalant allergens and immunoblotting profiles of buckwheat-allergic patients were studied. METHODS: Patients with suspected buckwheat allergy who attended the allergy clinic between January 1, 2006, and September 30, 2008, were evaluated. All patients underwent skin prick tests for a standard panel of inhalant and food allergens, prick-by-prick with buckwheat flour, buckwheat-specific IgE determinations, and double-blind placebo-controlled food challenge (DBPCFC) with buckwheat flour. Immunoblotting with buckwheat flour extract was performed on sera from buckwheat-allergic patients. RESULTS: Among 72 patients with suspected buckwheat allergy, 30 (41.7%) were sensitized to buckwheat and 24 had a positive DBPCFC. The mean buckwheat IgE level was 6.23 kUA/l (range, 0.16 to >100 kUA/l). Several IgE-binding proteins were identified and grouped into three patterns: a 16-kDa band in patients with predominantly gastrointestinal symptoms with grass and wheat flour co-sensitization, a 25-kDa band in patients with predominantly cutaneous symptoms and a low frequency of co-sensitization, and a 40-kDa band in patients with anaphylaxis and a low frequency of co-sensitization. CONCLUSIONS: Buckwheat allergy is an emerging food allergy in Italy. We identified three distinct patterns of clinical and laboratory characteristics, suggesting that specific allergens could be more frequently associated with clinical manifestations of different severity.

Anaphylaxis after eating Italian pizza containing buckwheat as the hidden food allergen.

A 20-year-old woman developed anaphylaxis after eating pizza on 4 different occasions in 2 restaurants. Both restaurants made their pizza dough with a mixture of wheat and buckwheat flours. A prick-to-prick test with buckwheat flour was positive. Skin prick tests and specific immunoglobulin E responses to soybean and peanut were weakly positive while the response to buckwheat was negative. We ruled out a pathogenic role for peanut and soybean because the patient usually eats both with no signs of allergic reaction. Double-blind, placebo-controlled food challenges with buckwheat flour were positive after the administration of a cumulative dose of 2.3 g of the culprit flour. To our knowledge, our report describes the first case of anaphylaxis after intake of buckwheat flour as the hidden allergen in pizza dough.