Allergenic Characterization of 27-kDa Glycoprotein, a Novel Heat Stable Allergen, from the Pupa of Silkworm, Bombyx mori

Boiled silkworm pupa is a traditional food in Asia, and patients with silkworm pupa food allergy are common in these regions. Still now only one allergen from silkworm, arginine kinase, has been identified. The purpose of this study was to identify novel food allergens in silkworm pupa by analyzing a protein extract after heat treatment. Heat treated extracts were examined by proteomic analysis. A 27-kDa glycoprotein was identified, expressed in Escherichia coli, and purified. IgE reactivity of the recombinant protein was investigated by ELISA. High molecular weight proteins (above 100 kDa) elicited increased IgE binding after heat treatment compared to that before heat treatment. The molecular identities of these proteins, however, could not be determined. IgE reactivity toward a 27-kDa glycoprotein was also increased after heating the protein extract. The recombinant protein was recognized by IgE antibodies from allergic subjects (33.3%). Glycation or aggregation of protein by heating may create new IgE binding epitopes. Heat stable allergens are shown to be important in silkworm allergy. Sensitization to the 27-kDa glycoprotein from silkworm may contribute to elevation of IgE to silkworm.

Profiles of IgE Sensitization to Der f 1, Der f 2, Der f 6, Der f 8, Der f 10, and Der f 20 in Korean House Dust Mite Allergy Patients

PURPOSE: Measurement of IgE specific to purified house dust mite (HDM) allergens may improve allergy diagnosis. This study aimed to investigate the sensitization profiles of Korean HDM allergic subjects suffering from respiratory allergy and atopic dermatitis (AD) to Der f 1, Der f 2, Der f 6, Der f 8, Der f 10, and Der f 20. METHODS: Recombinant HDM allergens were produced in Pichia pastoris (Der f 1) or Escherichia coli (5 allergens). IgE reactivity to the individual recombinant allergens and total extract of mite was assessed by ELISA. RESULTS: Der f 1 was recognized by 79.1%, Der f 2 by 79.1%, Der f 6 by 9.3%, Der f 8 by 6.2%, Der f 10 by 6.2%, and Der f 20 by 6.6% of the patients' sera tested, while the prevalence of IgE reactivity to total mite extract was 94.7%. Combination of Der f 1 and Der f 2 had a sensitivity of 87.6%. Specific IgE to Der f 2 alone was detected from 89.4% of HDM-sensitized respiratory allergy subjects and 92.3% to the combination of the 2 major allergens Der f 1 and Der f 2. However, sera from fewer patients with AD, namely 72.4% and 71.0%, recognized Der f 1 and Der f 2, respectively. The combination of 2 major allergens allowed diagnosis of 84.5% of the AD patients. No correlation between sensitization to specific allergens and HDM allergy entity was found. CONCLUSIONS: Der f 2 was the most frequently sensitized allergen among the HDM-sensitized respiratory and AD patients in Korea, and the combination of the group 1 and 2 major allergens increased the diagnostic sensitivity. Minor allergens did not significantly improve diagnostic sensitivity. However, further studies are needed to analyze the relationship between sensitization to other HDM allergens and the disease entity of the HDM allergy.