Sensibilização a alérgenos inalantes e alimentares em crianças brasileiras atópicas, pela determinação in vitro de IgE total e específica: Projeto Alergia (PROAL) / Sensitization to inhalant and food allergens in Brazilian atopic children by in vitro total and specific IgE assay: Allergy Project - PROAL

OBJETIVO: Determinar a freqüência de sensibilização a alérgenos inalantes e alimentares em crianças atendidas em serviços brasileiros de alergia. PACIENTES E MÉTODOS: IgE sérica total e específica (RAST) a alérgenos inalantes e alimentares (UniCAP® - Pharmacia) foram determinados em 457 crianças acompanhadas em serviços de alergia pediátrica e em um grupo de controles (n = 62). Resultados classe igual ou maior que 1 foram considerados positivos (R+). RESULTADOS: A freqüência de R+ foi significantemente maior entre os atópicos (361/457, 79 por cento) quando comparados aos controles (16/62, 25,8 por cento). Não houve diferenças quanto ao sexo. A prevalência de R+ entre os atópicos foi significantemente maior para todos os alérgenos avaliados. Os níveis séricos de IgE total foram significantemente mais elevados entre os atópicos com R+ quando comparados aos com R-. Comparando-se atópicos e controles, a freqüência de R+ para os principais alérgenos inalantes foi como segue: D. pteronyssinus = 66,7 versus 14,5 por cento (p < 0,05), D. farinae = 64,5 versus 17,8 por cento (p < 0,05), B. tropicalis = 55,2 versus 19,4 por cento (p < 0,05), barata = 32,8 versus 9,7 por cento (p < 0,05) e gato = 12 versus 8,1 por cento. Com os alimentos, observou-se: peixe = 29,5 versus 11,3 por cento (p < 0,05), ovo = 24,4 versus 4,8 por cento (p < 0,05), leite de vaca = 23,1 versus 3,2 por cento (p < 0,05), trigo = 20 versus 8,1 por cento (p < 0,05), amendoim = 14 versus 4,8 por cento (p < 0,05), soja = 11,8 versus 4,8 por cento (p < 0,05) e milho = 10,6 versus 4,8 por cento (p < 0,05). Segundo a idade, os R+ aos alimentares predominaram entre as crianças mais jovens, e o inverso ocorreu com os inalantes. CONCLUSÕES: Nesta população, predominou a sensibilização aos aeroalérgenos, sobretudo aos ácaros domiciliares, e os alimentos foram importantes em crianças mais jovens.

Phadiatop® no diagnóstico de alergia respiratória em crianças: Projeto Alergia (PROAL) / Phadiatop® in the diagnosis of respiratory allergy in children: Allergy Project - PROAL

OBJETIVO: Avaliar a positividade do Phadiatop® em crianças acompanhadas em serviços brasileiros de alergologia e compará-la aos resultados de IgE sérica específica a alérgenos inalantes e alimentares. CASUíSTICA E MÉTODO: Em 457 crianças acompanhadas em serviços de alergia pediátrica e um grupo de crianças controle não-alérgicas (n = 62), distribuídas em cinco faixas etárias, foram determinados em amostra de soro: Phadiatop® e IgE específica (RAST) a alérgenos inalantes e alimentares (UniCAP - Pharmacia®). RESULTADOS: O Phadiatop® foi positivo em 305 crianças atópicas (67,6 por cento) e em 25,8 por cento das controles (p < 0,001). Entre as crianças atópicas, a distribuição de positividade variou de acordo com a faixa etária: 7,9 por cento (24/305) entre as abaixo de 2 anos, 15,4 por cento (47/305) nas de 2 a 3 anos, 22,0 por cento (67/305) nas de 3 a 4 anos, 19,3 por cento (59/305) nas de 4 a 5 anos e 35,4 por cento (108/305) nas de 5 a 12 anos. Não houve concordância entre os alérgenos alimentares e a presença de Phadiatop® positivo. O estudo da relação entre os RAST positivos para alérgenos inalados e o Phadiatop® positivo mostrou melhores índices com os ácaros domiciliares (D. pteronyssinus, D. farinae e Blomia tropicalis). CONCLUSÕES: O Phadiatop®é método útil no diagnóstico de alergia aos ácaros domiciliares.

The value of a single skin prick testing for specific IgE Dermatophagoides pteronyssinus to distinguish atopy from non-atopic asthmatic children in the tropics.

In a tropical setting, where the prevalence of house dust mites (Dermatophagoides pteronyssinus) is high, we examined the advantage of a single battery of skin prick testing (SPT) for mite as a diagnostic tool by comparing the results of radio-allergo-sorbent-test (RAST) to distinguish allergic from non-allergic asthma in children. Fifty asthmatic children were enrolled in this study. After questioning the parents, SPT were carried out using house dust mite (D. pteronyssinus) and other 9 common aero-allergens and blood were taken for measuring the total IgE (PRIST) and specific IgE for mite (RAST). Dust was obtained from 14 asthmatic children's houses and mite counting was done under a high power microscope. With a daily temperature of 27.0 +/- 0.5 degrees C and a relative humidity of 80 +/- 1%, house dust mites were found in all samples; and 81% of the allergic asthmatic children had positive SPT for D. pteronyssinus. SPT for D. pteronyssinus had a sensitivity of 95% and specificity of 52% using RAST as gold standard and there was a moderate positive correlation between the size of SPT wheals and RAST scores for D. pteronyssinus (r = 0.67 and p = 0.001). The findings of this study suggest that SPT for mites should be used as a screening test and positive SPT should be confirmed by RAST.

Detection of IgE antibodies specific for 1-phenyl-2,3-dimethyl-3-pyrazoline-5-one by RAST: a serological diagnostic method for sensitivity to pyrazoline drugs.

Certain adverse reactions to pyrazoline drugs resemble IgE-mediated hypersensitivity. However, convincing evidence of antigen-antibody interactions is not fully demonstrated. In this study, IgE antibodies specific for 1-phenyl-2,3-dimethyl-3-pyrazoline-5-one have been found in 17 out of 19 serum samples from individuals sensitive to pyrazoline drugs with 4-aminoantipyrine discs by Radio Allergo Sorbent Test (RAST). In contrast, we have not found any positive results from 10 normal donors without sensitivity to pyrazoline drugs after ingestion of metamizol 500 mg/day for 14 days. Therefore, our results provide further evidence in favor of an IgE-dependent mechanism in patients suffering from sensitivity to pyrazoline drugs. The determination of specific IgE antibodies could be used as a serodiagnostics method.

The presence of specific IgE to salicyloyl and O-methylsalicyloyl in aspirin-sensitive patients.

Certain adverse reactions to aspirin (ASA), nonsteroidal anti-inflammatory drugs (NSAIDs) and pyrazoline derivatives resemble IgE-mediated hypersensitivity. However, convincing evidence of antigen-antibody interactions or of the inhibition of the cyclooxygenase pathway of arachidonic acid metabolism leading to an increase in the generation of leukotrienes (LTs) and a decrease in the generation of prostaglandins (PGs) was not fully demonstrated. In this study, two types of specific IgE antibodies have been found in 27 serum samples from 28 ASA-sensitive patients with salicyloyl-discs and O-methylsalicyloyl-discs by Radio Allergo Sorbent Tests (RAST). The positive rates were 96.4% and 71.4%, respectively. In contrast, no positive results could be found in 10 normal donors without ASA sensitivity after ingestion of ASA 500 mg/day for 14 days. Further investigation of the chemical structure of epitopes was done by cross inhibition studies. Our results are an increasing evidence in favour of an IgE-dependent mechanism in patients suffering from ASA sensitivity. Hopefully, the determination of specific IgE antibodies will be a safe diagnostic method of ASA sensitivity in vitro.

A study on antigenic and allergenic changes during storage in three different biological extracts.

The stability of three allergens common in tropical countries was evaluated under different storage conditions. Prosopis juliflora (PJ), Rhizopus nigricans (RN), and wheat dust (WD), were taken as representatives of various groups of allergens viz, pollen, fungi and dust. The extracts were stored in buffer containing phenol (0.4%) or glycerol (50%) at temperatures ranging from 4-55 degrees C for 15 to 60 days. Protein content of PJ extract was reduced remarkably when it was stored at 40 degrees C for 45 days. Thin layer isoelectric focusing and rocket immunoelectrophoresis of PJ showed that certain antigenic proteins degrade rapidly even at 25 degrees C as early as day 15. However, two to three proteins of PJ remain stable at a higher temperature (40 degrees C) for two months. Relative radioallergosorbent test (RAST) inhibition showed substantial loss of allergenic activity in all the three extracts, when stored at higher temperatures (25-55 degrees C) even for short durations, i.e., 15 days. Extracts (PJ and RN) containing 50% glycerol were found to be stable, retaining more than 50% activity, even when stored at 55 degrees C for 40 days, while extracts without glycerol lost more than 75% of their allergenic activity. However, addition of glycerol did not change the stability of wheat dust allergenic extract. The present findings indicate that allergenic extracts behave differently when stored. Hence, the stability of each extract should be determined individually.