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)

Bet v 1-like pollen allergens of multiple Fagales species can sensitize atopic individuals.

BACKGROUND: In the temperate climate zone of the Northern hemisphere, Fagales pollen allergy represents the main cause of winter/spring pollinosis. Among Fagales trees, pollen allergies are strongly associated within the Betulaceae and the Fagaceae families. It is widely accepted that Fagales pollen allergies are initiated by sensitization against Bet v 1, the birch pollen major allergen, although evidence is accumulating that the allergenic activity of some Bet v 1-like molecules has been underestimated. OBJECTIVE: To investigate the allergenic potential of the clinically most important Fagales pollen allergens from birch, alder, hazel, hornbeam, hop-hornbeam, oak, beech and chestnut. METHODS: To obtain the full spectrum of allergens, the three previously unavailable members of the Bet v 1-family, hop-hornbeam Ost c 1, chestnut Cas s 1 and beech Fag s 1, were identified in the respective pollen extracts, cloned and produced as recombinant proteins in E. coli. Together with recombinant Bet v 1, Aln g 1, Car b 1, Cor a 1 and Que a 1, the molecules were characterized physicochemically, mediator release assays were performed and IgE cross-reactivity was evaluated by ELISA and Immuno Solid-phase Allergen Chip (ISAC) IgE inhibition assays. RESULTS: All allergens showed the typical Bet v 1-like secondary structure elements, and they were all able to bind serum IgE from Fagales allergic donors. Strong IgE binding was observed for Betuloideae and Coryloideae allergens, however, cross-reactivity between the two subfamilies was limited as explored by inhibition experiments. In contrast, IgE binding to members of the Fagaceae could be strongly inhibited by serum pre-incubation with allergens of the Betuloideae subfamily. CONCLUSIONS AND CLINICAL RELEVANCE: The data suggest that Bet v 1-like allergens of the Betuloideae and Coryloideae subfamily might have the potential to induce IgE antibodies with different specificities, while allergic reactions towards Fagaceae allergens are the result of IgE cross-reactivity.

Sublingual immunotherapy in tree pollen allergy. Double-blind, placebo-controlled study with a biologically standardised extract of three pollens (alder, birch and hazel) administered by a rush schedule.

BACKGROUND: sublingual immunotherapy has been recognised as safe and effective but it is still poorly documented in tree pollen allergy. Allergy to alder, birch and hazel is important in Northern European countries but its clinical relevance is increasing in Southern Europe. METHODS: thirty patients, selected and observed for one pollen season, were randomised to receive placebo (15 patients) or active treatment (15 patients). Twenty-seven patients completed the first year and 24 of them were treated with active therapy during the second year of the study in comparison to a parallel group of ten patients treated only with drugs. Symptom and drug scores during each pollen season, birch-specific IgE, changes in skin test reactivity, changes in specific Nasal Provocation Test and the daily average pollen count for the relevant trees were considered for the assessment of the efficacy of the treatment. RESULTS: both active and placebo group showed a statistically significant improvement in scores in comparison to the previous year, under a lower allergenic pressure. The improvement was higher in the active group (76.04 % reduction of drugs) but not significantly different from that registered in the placebo group (37.05 % reduction). In the open phase of the study, treated patients showed significantly better scores in comparison to the control group. No significant changes in skin reactivity, specific IgE and Nasal Provocation Test were registered. SLIT tolerance was very good. CONCLUSIONS: our data show a better but not statistically significant clinical outcome for patients actively treated with SLIT, but the placebo effect and the year-by-year variability of the environmental allergenic load in our small-size pilot study do not allow for a conclusive statement about the efficacy of this form of therapy.

Sublingual immunotherapy in tree pollen allergy. Double-blind, placebo-controlled study with a biologically standardised extract of three pollens (alder, birch and hazel) administered by a rush schedule

Background: sublingual immunotherapy has been recognised as safe and effective but it is still poorly documented in tree pollen allergy. Allergy to alder, birch and hazel is important in Northern European countries but its clinical relevance is increasing in Southern Europe. Methods: thirty patients, selected and observed for one pollen season, were randomised to receive placebo (15 patients) or active treatment (15 patients). Twenty-seven patients completed the first year and 24 of them were treated with active therapy during the second year of the study in comparison to a parallel group of ten patients treated only with drugs. Symptom and drug scores during each pollen season, birch-specific IgE, changes in skin test reactivity, changes in specific Nasal Provocation Test and the daily average pollen count for the relevant trees were considered for the assessment of the efficacy of the treatment. Results: both active and placebo group showed a statistically significant improvement in scores in comparison to the previous year, under a lower allergenic pressure. The improvement was higher in the active group (76.04 % reduction of drugs) but not significantly different from that registered in the placebo group (37.05 % reduction). In the open phase of the study, treated patients showed significantly better scores in comparison to the control group. No significant changes in skin reactivity, specific IgE and Nasal Provocation Test were registered. SLIT tolerance was very good. Conclusions: our data show a better but not statistically significant clinical outcome for patients actively treated with SLIT, but the placebo effect and the year-by-year variability of the environmental allergenic load in our small-size pilot study do not allow for a conclusive statement about the efficacy of this form of therapy (AU)

Antecedentes: la inmunoterapia sublingual ha sido reconocida como segura y eficaz pero está aún pobremente documentada sobre alergia al polen de árboles. La alergia al aliso, abedul y avellano es importante en los países del norte de Europa, pero su relevancia clínica está aumentando en el sur de Europa. Métodos: 30 pacientes seleccionados y observados a lo largo de una época de polinización, fueron aleatorizados para recibir placebo (15 pacientes) o tratamiento activo (15 pacientes). Completaron el primer año 27 pacientes y 24 de ellos fueron tratados con inmunoterapia activa durante el segundo año del estudio, comparándose con un grupo paralelo tratado solamente con medicamentos. El registro de síntomas y medicamentos durante cada época de polinización, IgE específica al aliso, cambios en la reactividad de la piel, cambio en la prueba de provocación nasal específica y el recuento diario de pólenes de los árboles relevantes fueron considerados para evaluar la eficacia del tratamiento. Resultados: tanto el grupo activo como el placebo mostraron una mejora estadísticamente significativa en los registros, en comparación al año anterior, bajo una menor presión alergénica. La mejoría fue mayor en el grupo activo (76,04 por ciento de reducción de medicamentos) que en el placebo (37,05 por ciento de reducción). En la fase abierta del estudio, los pacientes tratados mostraron una puntuación significativamente mejor que el grupo control. No se registraron cambios significativos en la reactividad de la piel, IgE específica y prueba de provocación nasal específica. La tolerancia del SLIT fue muy buena.Conclusiones: nuestra información muestra un mejor, que no estadísticamente significativo, resultado clínico, en los pacientes tratados con el tratamiento SLIT activo, pero el efecto placebo y la variabilidad de año en año de la carga ambiental alergénica en nuestro pequeño ensayo piloto, no permiten realizar una afirmación concluyente sobre la eficacia de este tipo de terapia (AU)

Sublingual immunotherapy in Parietaria pollen-induced rhinitis: a double-blind study.

A double-blind, placebo-controlled study of immunotherapy was conducted in 31 patients with allergic rhinitis due to Parietaria pollen to evaluate the efficacy and safety of high doses of allergen via the sublingual route. The patients were assessed before and after a 10-month period of treatment by clinical (symptom-medication scores and specific nasal reactivity) and immunological (total IgE, specific IgE, IgG and IgG4 antibodies) parameters. High doses of Parietaria extract corresponding to a cumulative dose of 105 BU for each patient were administered with negligible side effects. The actively treated patients had significantly lower medication scores than those on placebo (p < 0.05) when the maximum pollen count was recorded, and at the end of the trial they showed a significant decrease in nasal reactivity (p < 0.02) and a significant increase in serum specific IgG4 (p = 0.02). No differences were detected in any of these parameters in the placebo group. Possible explanations for the mechanisms of sublingual immunotherapy are proposed.

Is the allergen-inhalation challenge predictive of the severity of seasonal asthmatic exacerbations?

Fifteen asthmatic patients sensitized to Parietaria pollen were studied. Before the pollen season they underwent an allergen-inhalation challenge which was preceded and followed by a methacholine-inhalation challenge. Pollen count, symptom score, and drug consumption were monitored daily throughout the study. A severity score was obtained by adding symptom score and drug consumption. Patients underwent a third methacholine challenge during the pollen season, after they had been exposed to a high atmospheric concentration of pollen. The severity score during the first period of the pollen season was significantly correlated with both the early and the late asthmatic responses to the allergen observed before the season (r2 = 0.50; P < 0.005). Bronchial sensitivity to methacholine was significantly increased both after allergen challenge and after seasonal exposure, but these increases correlated neither with each other nor with the severity score. We conclude that bronchial responses to experimental exposure to allergens, but not the changes in nonspecific airway responsiveness, can, in part, predict the severity of asthma exacerbation during the pollen season.

Allergy to pollens from Betulaceae and Corylaceae in a Mediterranean area (Genoa, Italy)--a ten-year retrospective study.

Allergy to pollens from Betulaceae and Corylaceae is becoming a leading problem in Genoa, a northern Mediterranean area in Italy. The results of a 10-year retrospective study on combined observations both on the aerobiological presence of Betulaceae and Corylaceae pollens (Alnus, Corylus, Ostrya) and on the incidence of positive SPT in the allergic population living in the same area are reported. Among 3473 patients suffering from seasonal respiratory allergy with positive SPT to one or more pollens, 558 (16.06%) showed SPT positivity to Betulaceae and/or Corylaceae pollens, both isolated and associated with other allergens. These patients suffered from winter or early spring hay fever, with a high incidence of bronchial asthma. A statistically significant increase (0.02 < p < 0.05) in the number of these sensitizations from 1981 to 1990 has been observed. Some possible explanations for this phenomenon, including an increase in the total amount of local airborne pollens, are suggested. About 24% of the patients with positive SPT to these pollens referred oral allergic syndrome associated with the ingestion of some foods, especially apples and nuts, with or without other additional clinical symptoms.

Effect of seasonal exposure to pollen on specific bronchial sensitivity in allergic patients.

Bronchial provocation tests with aerosol of birch extract were performed before and after pollen season in 11 sensitized subjects. Changes of metacholine bronchial responsiveness and serum-specific IgE level were also assessed. In five patients who did not take steroids to control their symptoms, both early and late asthmatic responses to inhaled allergen were enhanced after season, whereas IgE serum level, but not methacholine sensitivity, was significantly increased. In six patients who needed steroids, neither responses to allergen nor IgE serum level and methacholine sensitivity were significantly changed after season. For the whole group, the increase in immediate bronchial sensitivity to allergen was positively correlated with the increase in specific IgE antibodies. We conclude that seasonal exposure to pollen has, in sensitized patients, a priming effect on bronchial mucosa that may be blunted by steroid treatment. The increased production of specific IgE antibodies appears to be an important mechanism for this priming effect.

Late asthmatic reaction to perennial and seasonal allergens.

Twelve patients with asthma sensitized to Dermatophagoides pteronyssinus and Parietaria judaica were studied. Patients were challenged before (winter), during (summer), and after (autumn) Parietaria-pollen season. Early asthmatic reaction was positive for both allergens, and the provocative dose causing a 15% decrease of FEV1 was similar in all seasons. The provocative dose of methacholine causing a 15% decrease of FEV1 and specific IgEs for both allergens were also not significantly different throughout the time of study. Late asthmatic reaction (LAR) to Dermatophagoides occurred in eight of 12 patients in winter, in six of nine in summer, and in five of six patients in autumn. The severity of LAR, expressed as the maximum fall of FEV1 3 to 8 hours after challenge, was not significantly different between seasons. LAR to Parietaria occurred in only one of 12 patients in winter, in six of 11 in summer, and in one of six patients in autumn. In summer, LAR to Parietaria was significantly more severe than in winter. In both winter and autumn, but not in summer, LAR to Dermatophagoides was significantly more severe than to Parietaria. We conclude that LAR is allergen specific, and natural exposure has a priming effect on LAR.

Allergy to Parietaria pollen and month of birth.

It has been suggested that the season of birth is a predisposing factor for allergic sensitization. In the last few years many authors in different countries have found a statistically significant correlation between the month of birth and the subsequent allergy for grasses and birch pollens and house dust mites. Nevertheless, other investigators failed to confirm these results. The aim of the present study is to assess the relationship between the season of birth and the development of respiratory allergy to pollen of Parietaria, an Urticacea plant characteristic of Mediterranean flora, which is the most important hay fever producing one in our country. Among the patients who visited the Servizio Autonomo di Allergologia at the St. Martino Hospital (Genoa, Italy) in the year 1986, 264 subjects (113 F and 151 M, 5-35 years of age, all born and living in Genoa and its suburbs) were selected. The birth month of these patients, affected by rhinitis and/or bronchial asthma and with positive prick-test only toward Parietaria pollen, was recorded and compared with that of the population born in Genoa in the same years. Statistical evaluation made by X2 test showed the absence of a statistically significant relationship between the birth in the pollen season (April-July) and the pollinosis, with the exception of the month of May. The reasons of the discrepances observed between the behaviour of Parietaria pollen and that of the other pollens, grasses and birch, described in the above studies, are discussed.