[Contribution of serum total immunoglobulin E measurement in the diagnosis of respiratory allergic diseases]

Serum total IgE measurement is one of the first allergic inflammation marker test. It has been currently used for the diagnosis of allergy. However, when it has been widely used in clinical practice, we discover its limit in the diagnosis of allergic disease. We carried a retrospective study about 1111 consecutive patients, seen in the Allergology Unit of the Home Ministry Hospital with suspicion of atopic disease. The aim of our study is to evaluate the contribution of serum total IgE measurement in the diagnosis of respiratory allergic diseases. Our population was divided into three groups. Group A: 771 allergic symptomatic subjects [371 children with mean age of 7.8 +/- 3.4 years and 467 adults with mean age of 30.1 +/- 6.6 years]. Group B: 117 controls [70 children with mean age of 6.6 +/- 3 years, and 47 adults with mean age of 30.7 +/- 6 years]. 221 patients with doubtful diagnosis of allergy were excluded [group C]. If we consider the cut-off I of 150 UI [for adults], 75% of allergic subjects have elevated serum total IgE, 62% of adults and 77.6% of children. When doubling the cut-off [cut-off II], 49% of allergic subjects have serum total IgE over 300 UI/ml, 36% of adults and 57% of children. In the control group: 35.8% of patients have total IgE over the cut-off value I and 17% over the cut-off value II. The variation of serum total IgE was related in allergic subjects to the type and the number of symptoms. The levels of total IgE were higher in asthma than in rhinitis and more elevated if the patient has several symptoms. With cut-off I we found a quite good sensibility of the test of 75% [62% in adults and 77.6% in children] and a poor specificity of 64% [68% in adults and 61% in children], with a negative predictive value of 28% and a positive predictive value of 93%. When doubling the cut-off, the sensibility falls to 49% and the specificity was improved at 82%. The serum total IgE measurement was in agreement with prick-tests in 80% of cases and with Phadiatop in 56% of cases if we consider cut-off I. Our results showed a large overlapping of serum total IgE in both allergic and control populations. The measurement of serum total IgE is not helpful for the diagnosis of allergic respiratory diseases because it has a quite good sensibility, a poor specificity and a poor negative predictive value. The test was more sensible and less specific in children

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.

Serum IgE levels and its clinical correlation with varying patterns of bronchial asthma and nasal allergy.

In a study of 847 cases of bronchial asthma and nasal allergy frequent association with raised serum IgE was noticed. Degree of atopy (as judged by skin allergy tests), age, sex and duration of disease tended to influence IgE levels in asthmatics. Both extrinsic and intrinsic varieties of asthma showed similar raised serum IgE levels. In subjects with nasal allergy alone, the values were considerably lower but still much higher than found in control patients.

Determinación de poblaciones y subpoblaciones linfocitarias en pacientes con enfermedad respiratoria inmunoalérgica / Determination of groups and subgroups lymphocytic in patients with immunoalergic respiratory disease

Se determinaron los niveles de IgE séricos y se cuantificaron las poblaciones de linfocitos B (LB) y T (LT) y las subpoblaciones T4 (CD4+) y T8 (CD8+) en 20 pacientes con enfermedad respiratoria inmunoalérgica (rinosinusitis y/o asma bronquial). Los niveles de IgE se encontraron aumentados en el 90 por ciento de los pacientes (valor promedio 412 Ul/ml; rango 56-1000 Ul/ml). El recuento de LB estuvo normal o disminuido; en cuanto a la población de LT, se observó la existencia de una relación entre niveles bajos de IgE y LT normales y niveles altos de IgE y LT bajos. La subpoblación de linfocitos T8 estuvo normal en el 50 por ciento de los pacientes estudiados. Fueron significativos los resultados obtenidos al estudiar la subpoblación T4, que se encontró disminuída en el 80 por ciento de los pacientes. Quizá un estudio discriminativo de las subclases que la constituyen explicaría los hallazgos inmunológicos en estos pacientes. De acuerdo a estos resultados, se puede concluir que es muy importante el estudio del sistema inmune del paciente antes de implementar la inmunoterapia específica, tratando de emplear un egente terapéutico que normalice la población de linfocitos afectada y conseguir el mayor éxito en el tratamiento