Ana o 2, an 11S globulin (legumin), and Ana o 3, a 2S albumin, in cashew nut induce epicutaneous sensitization in mice

Food allergy is increasing worldwide, and sensitization through the skin is an important route of disease onset. However, the principal molecules driving epicutaneous sensitization to cashew nut remain unclear. Here, we established a BALB/c mouse model of epicutaneous sensitization and investigated major reactive antigens. Cashew nut-specific IgE was significantly higher in the cashew nut group at weeks 4 and 5, and cashew nut-specific IgG1 was significantly higher at weeks 3, 4, and 5. Immunoblotting showed antibody binding across multiple molecular weight regions. Immunoreactivity-guided fractionation followed by LC-MS/MS identified Ana o 3 (2S albumin; ∼10 kDa) and Ana o 2 (11S globulin; ∼50 kDa) as major IgG1-reactive antigens. Cross-reactivity was strongest with pistachio. Heating (160°C, 30 min) reduced immunoreactivity of the recoverable extract in coated-antigen assays under the present extraction conditions. These findings identify Ana o 2 and Ana o 3 as major reactive antigens in this mouse model.