Parasite Infections, Allergy and Asthma: A Role for Tropomyosin in Promoting Type 2 Immune Responses.

INTRODUCTION: The relationship of parasite infections and promotion or protection from allergy and asthma is controversial. Currently, over 1.5 billion people are infected with parasites worldwide, and Ascaris lumbricoides is the most frequent soil-transmitted helminth. OBJECTIVES: To evaluate the biological activity of recombinant A. lumbricoides tropomyosin and investigate IgE cross-reactive responses to tropomyosins by means of microarray methodology for the detection of sensitization to allergen components. METHODS: Forty patients 12-75 years of age (25 males) with asthma and/or rhinitis and 10 nonallergic control subjects participated in this study. All patients presented positive skin tests to cockroach extracts and underwent skin prick testing (SPT) with recombinant (r) tropomyosins rPer a 7 from Periplaneta americana and rAsc l 3 from A. lumbricoides, at 10 µg/mL. IgE to cockroach and parasite tropomyosins were measured by chimeric ELISA and ImmunoCAP-ISAC, and total IgE was quantitated by ImmunoCAP. Agreement of results was assessed by κ statistics. RESULTS: Recombinant A. lumbricoides showed biological activity, inducing positive skin tests in 50% patients with asthma and/or rhinitis. IgE to cockroach and parasite tropomyosins were detected in 55-62% of patients. There was good-to-excellent agreement of results of SPT and IgE measurements by ELISA and ImmunoCAP-ISAC, with κ indices of 0.66-0.95. No skin test reactivity or IgE antibodies to tropomyosins were found in nonallergic individuals. CONCLUSIONS: Our results suggest that IgE responses to tropomyosin from A. lumbricoides may enhance reactivity to homologous allergens upon exposure by inhalation or ingestion, promoting allergic reactions and asthma, or increasing the severity of these clinical conditions.

Evaluation of the concentration of allergens from mites in fur and households dust of dogs with atopic dermatitis / Avaliação da concentração de alérgenos provenientes de ácaros na pelagem e na poeira de domicílios de cães com dermatite atópica

This study evaluated the concentration of Der p 1, Der f 1 and Blo t 5 in the fur and households of 20 dogs with atopic dermatitis (AD) and 20 healthy dogs. The diagnosis of AD was clinical based on Favrot's criteria. Dust samples were collected with a domestic vacuum cleaner. For each site, 1m2 was vacuumed for 2 min. The samples were collected in separate filters, transferred into plastic containers, sealed and kept frozen until ELISA analysis. In the fur of atopic dogs the average concentration of Der p 1 was 0.25µg/g compared to 0.03µg/g in healthy dogs. In households with atopic dogs the highest concentrations of Der p 1 were found in carpets (2.18µg/g), followed by couches (1.53µg/g), beds (1.14µg/g), dogs' bed linen (0.64µg/g) and floors (0.14µg/g). The concentrations of Der p 1 on carpets, couches and beds were significantly higher than in atopic dogs' fur (p<0.05). There was no statistical difference when comparing the concentrations of Der f 1 and Blo t 5 in different environments of atopic dogs (p>0.05). The concentrations of Der p 1, Der f 1 and Blo t 5 were equivalent in atopic and non-atopic dog's households. Among the allergens studied, Der p 1 was the most commonly found, predominantly in carpets and couches.(AU)

O presente estudo avaliou a concentração de Der p 1, Der f 1 e Blo t 5, na pelagem e no ambiente domiciliar de cães com dermatite atópica (DA). Para tal, foram selecionados 20 cães com DA e 20 cães saudáveis, e seus domicílios. O diagnóstico de DA foi baseado nos critérios de Favrot. As amostras de poeira foram colhidas com um aspirador de pó doméstico. Para cada local de colheita, foi aspirado 1m2 por dois minutos. As amostras foram recolhidas em filtros separadamente, transferidas para envelopes plásticos, seladas e mantidas congeladas até serem analisadas pelo método de ELISA. Na pelagem dos cães com DA, a concentração média de Der p 1 foi de 0,25µg/g de poeira e nos cães saudáveis foi de 0,03µg/g. No ambiente de cães com DA, o Der p 1 foi encontrado em maior concentração média no tapete (2,18 µg/g), seguido pelo sofá (1,53g/g), cama (1,14µg/g) e roupa de cama dos cães (0,64µg/g) e chão (0,14µg/g). As concentrações de Der p 1 no tapete, sofá e cama dos cães foram significativamente maiores que na pelagem de cães com dermatite atópica (p<0,05). Enquanto que, não houve diferença estatística quando comparadas as concentrações de Der f 1 e Blo t 5 nos diferentes ambientes avaliados (p>0,05). As concentrações de alérgenos Der p 1, Der f 1 e Blo t 5 se equivaleram em ambientes de cães com DA e saudáveis. Entre os alérgenos estudados, o Der p 1 foi o mais comumente encontrado, prevalecendo no tapete e no sofá.(AU)

Recombinant allergens for diagnosis of cockroach allergy.

Molecular cloning of cockroach allergens and their expression as recombinant proteins have allowed a better understanding of the mechanisms of cockroach allergic disease. Recombinant cockroach allergens have been used for skin testing or in vitro methods to measure IgE antibody levels in serum. Early studies evaluating selected U.S. patients revealed that a cocktail of four cockroach allergens, Bla g 1, Bla g 2, Bla g 4, and Bla g 5, would identify 95 % of cockroach allergic patients. More recent studies pointed to an important role of sensitization to tropomyosin among certain populations, and suggested that a cocktail of five allergens Bla g 1 and/or Per a 1, Bla g 2, Bla g 4, Bla g 5, and Bla g 7, and/or Per a 7, would be expected to diagnose 50- 64 % of cockroach-allergic patients worldwide. Variation in IgE reactivity profiles could be in part due to IgE responses to cross-reactive homologous allergens from different origins. The availability of purified natural or recombinant cockroach allergens provides the capacity to improve diagnosis of cockroach allergy and to develop novel forms of immunotherapy for cockroach-allergic patients.

Alérgenos recombinantes: papel no diagnóstico e na imunoterapia alérgeno-específica / Recombinant allergens: role in diagnosis and in allergen-specific immunotherapy

Nos últimos 30 anos tem havido um avanço notável na identificação, purificação e expressão recombinante de alérgenos relevantes das mais variadas fontes, incluindo ácaros, insetos, mamíferos, polens, alimentos, fungos, látex e outras fontes. Estes avanços resultaram na utilização crescente de alérgenos purificados, naturais ou recombinantes, para melhorar o diagnóstico de alergia pelos métodos que dispomos, incluindo os testes cutâneos de hipersensibilidade imediata, e os métodos in vitro para medida de anticorpos IgE específicos, como ImmunoCAP, ImmunoCAP-ISAC, ELISA e MARIA. Mais recentemente, o uso de alérgenos recombinantes de pólen de bétula (rBet v 1) e de gramas (coquetel de 5 alérgenos) em imunoterapia foi relatado como seguro e eficaz, com resultados comparáveis aos obtidos usando extratos naturais, em pacientes com rinoconjuntivite alérgicos a polens. No presente artigo, apresentamos revisão atualizada do uso de alérgenos recombinantes em diagnóstico de alergia e em imunoterapia alérgeno-específica, incluindo novas estratégias de imunoterapia. Focalizamos na avaliação crítica de estudos que investigaram sensibilidade, especificidade, reatividade cruzada e valor prognóstico de métodos diagnósticos com uso de alérgenos recombinantes versus extratos naturais; nas recomendações atuais para o uso destes novos métodos na prática clínica; e na revisão de estudos clínicos com imunoterapia usando alérgenos recombinantes realizados até o momento.

Over the past 30 years, a great deal of progress has been made in the identification, purification,and recombinant expression of relevant allergens from various sources, including mites, insects,mammals, pollens, foods, fungi, latex, and other sources. These new developments have resultedin an increasing use of purified allergens, either natural or recombinant, to improve the diagnosisof allergy via the methods currently available, including skin tests and in vitro tests for measuringspecific IgE antibodies, e.g., ImmunoCAP, ImmunoCAP-ISAC, ELISA, and MARIA. More recently,the use of recombinant allergens from birch pollen (rBet v 1) and from grass pollen (a cocktailof five allergens) in immunotherapy has been reported to be safe and effective, with resultscomparable to those obtained with natural extracts in patients with rhino-conjunctivitis due topollen allergy. In the present article, we present an up-to-date review on the use of recombinantallergens in the diagnosis of allergy and in allergen-specific immunotherapy, including newstrategies for immunotherapy. We focus on the critical analysis of studies that have investigatedsensitivity, specificity, cross-reactivity, and the prognostic value of diagnostic methods that includerecombinant allergens versus natural extracts; on current recommendations for the use of thesenew methods in clinical practice; and on the review of clinical studies using immunotherapy withrecombinant allergens performed to date.

Efficacy of recombinant allergens for diagnosis of cockroach allergy in patients with asthma and/or rhinitis.

BACKGROUND: Immunoglobulin E (IgE) reactivity to individual allergens among cockroach-allergic patients has revealed wide variability. The aim of this study was to assess the effectiveness of recombinant cockroach allergens for skin testing, and to determine sensitization profiles among cockroach-allergic patients living in Brazil. METHODS: Fifty-seven cockroach-allergic patients with asthma and/or rhinitis were recruited. Skin testing with recombinant (r) allergens from Periplaneta americana (rPer a 1 and rPer a 7) and Blattella germanica (rBla g 2, rBla g 4 and rBla g 5) were performed at 10 µg/ml and 5 µg/ml (rPer a 1). IgE antibodies to rPer a 7 and rPer a 1 were quantitated by ELISA. RESULTS: Of 57 patients tested, 3 (5.3%), 24 (42.1%), 4 (7%), 3 (5.3%) and 4 (7%) showed positive reactions to rPer a 1, rPer a 7, rBla g 2, rBla g 4 and rBla g 5, respectively. Twenty-eight patients (49.1%) had positive tests to at least one allergen. In keeping with skin test results, 31/57 patients (54.4%) and 5/55 patients (9%) had detectable IgE to rPer a 7 and rPer a 1, respectively. Levels of IgE to rPer a 7 were higher in patients with positive tests to rPer a 7 than those with negative tests (geometric mean 13.2 and 1.8 IU/ml, p < 0.05). There was good concordance of results of skin tests and measurements of serum IgE to rPer a 7. CONCLUSION: IgE reactivity to rPer a 7 (P. americana tropomyosin) was dominant among patients in Brazil. However, 50% of the patients did not present reactivity to any of the recombinant allergens tested.

Measurement of IgE antibodies to shrimp tropomyosin is superior to skin prick testing with commercial extract and measurement of IgE to shrimp for predicting clinically relevant allergic reactions after shrimp ingestion.

BACKGROUND: Shrimp is a frequent cause of food allergy. Tropomyosin is the major allergen in shrimp, and it shares homology to tropomyosins from other crustaceans, dust mites, cockroach, and parasites. OBJECTIVE: The aim of this study was to determine the value of detection of IgE to shrimp tropomyosin in the diagnosis of shrimp allergy. METHODS: We have studied 35 patients with asthma, rhinitis, or both who were sensitized to Dermatophagoides pteronyssinus. All subjects underwent skin prick testing in addition to double-blind, placebo-controlled food challenges (DBPCFC); oral open challenges; or both with shrimp. Measurements of IgE to shrimp and shrimp tropomyosin were carried out by means of CAP and chimeric ELISA, respectively. RESULTS: Oral challenges confirmed the diagnosis of shrimp allergy in 7 patients. IgE measurement to shrimp tropomyosin was positive in 71.4% of the patients with shrimp allergy. Of the 28 patients without shrimp allergy, only 7.1% (2/28) had IgE to shrimp tropomyosin compared with 25% (7/28) who had IgE to shrimp and 35.7% (10/28) who had positive skin prick test responses to shrimp. Sensitivity was similar for all 3 methods (71.4%); in contrast, specificity of IgE to shrimp tropomyosin (92.8%) was greater than that of IgE to shrimp (75%) and skin prick testing (64.2%). With regard to diagnostic efficiency, measurement of IgE to shrimp tropomyosin was superior to measurement of IgE to shrimp and skin prick testing (88.5%, 74.2%, and 65.7%, respectively). CONCLUSION: Use of measurements of IgE to shrimp tropomyosin provided added value to the diagnosis of shrimp allergy.