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Background: Atopy is usually defined as the genetic propensity to produce IgE antibodies (Abs) specific to common environmental allergens. The aim of this study was to evaluate impacts of the number of allergens examined on prevalence of atopy., Methods: Subjects comprised 116 healthy controls, 104 patients with asthma, 294 patients with COPD, 64 patients with sarcoidosis and 218 residents of Kamishihoro town. Total serum immunoglobulin E and antigen-specific IgE antibody levels for 26 common allergens were examined. Atopy was defined as positive IgE Abs specific to > or =1 allergen. We serially increased the number of allergens to define atopy from the most common allergens in order of frequency, and changes in prevalence of atopy were evaluated. In residents of Kamishihoro, betula pollen antigen was also examined, as this antigen is very common in the town., Results: The increasing prevalence of atopy was dramatically reduced relative to the number of allergens examined. Among residents of Kamishihoro town, 5 cases displayed specific IgE Abs to this allergen alone and prevalence of atopy was increased 2.3 percents., Conclusion: When atopy was defined as the production of specific IgE Abs to common allergens, roughly 10 of the most common allergens may cover common environmental allergens.

An IgE RIA kit (Sandwich method; Dainabott), is used to obtain the following results. (1) Standard curve: Since the range of reproduction rate show 3.16-7.07% (C.V.), the curve become steep. (2) Incubations under controlled situation: Both of the incubations are controlled at 15-30 degrees C for 2 h. (3) Reproducibility test: Coefficients of variation (C.V.) of intra-assay and inter-assay variation are 2.32-3.94% and 2.92-3.92% respectively. (4) Recovery test: A result of the recovery test range between 100.1-101.7%. (5) Dilution test: Multiple dilution effects are observed. (6) Average counts of the serum IgE for the controlled and diseased groups: The average counts of the serum IgE for the controlled group, atopic diseased group, allergic rhinitis group and allergic bronchial asthma are 144.9 +/- 183.2 IU/ml, 1,099.0 +/- 2,782.4 IU/ml, 1,150.9 +/- 2,063.3 IU/ml and 600.7 +/- 686.4 IU/ml respectively. The value of the diseased groups have tendency to show higher averages than the controlled group. Since the controlled and diseased groups show wide distributions of the serum IgE level, there is no significant difference of two variations. However the diseased groups have tendency to show higher ratio of the serum IgE level in blood than the controlled groups. These basic researches are quite meaningful, because they are able to apply for a supplemental diagnosis of the atopic and parasitic disease.