Sensitization pattern to environmental allergens in a Japanese population

BACKGROUND: We previously described the prevalence of allergen-specific IgE in a general population of Japanese adults. OBJECTIVE: We sought to elucidate allergen sensitization patterns in this population. METHODS: Serum samples had been obtained from 800 blood donors aged 20 to 59 years and living in Tokyo, Japan, in 2005 and stored in the Japanese Red Cross Society. These samples were examined for IgE levels, total and specific for 23 allergens or allergen sources correlated with allergic airway diseases using the ImmunoCAP method. Exploratory and confirmatory factor analyses were performed to uncover the relationship among allergen-specific IgE based on their titers. Hierarchical cluster analysis was executed using Ward’s method based on standardized factor scores identified through factor analysis. RESULTS: Exploratory factor analysis revealed 6 categories of allergen-specific IgE: specific to 2 types of animals (insects and Dermatophagoides pteronyssinus/animal dander), 2 types of pollens (group 1 [Japanese cedar and cypress] and group 2 [alder, grass, and weeds]), and 2 types of microorganisms (fungi and commensal microorganisms on the skin). The Japanese population was categorized into 3 clusters: (A) nonatopic type, (B) house dust mite–dominant sensitization type, and (C) panatopic type. The panatopic group could be further classified into 2 subclusters positive and negative for fungal sensitization. CONCLUSIONS: This study demonstrated that a Japanese population could be divided into 3 clusters according to the sensitization pattern to 6 types of allergens.