Identification of the basic subunit of Ara h 3 as the major allergen in a group of children allergic to peanuts

Background Several proteins have been identified as peanut allergens; among them, Ara h 1 (7S globulin) and Ara h 2 (2S globulin) are usually considered the major allergens. Objective To identify the major allergens in a group of children selected for their specific pattern of immunoreactivity. Methods We identified the dominant allergen by using (1) amino acid sequencing of the bands that show the strongest IgE immunoreactivity in 1-dimensional electrophoresis and immunoblotting and (2) specific animal IgGs raised against the dominant immunoreactive band to pinpoint the allergen(s) in peanut proteins separated by 2-dimensional electrophoresis and immunoblotting. To confirm these data, we further examined the peanut proteome using serum samples from the children with the unusual immunoreactivity. Results We found a group of children with marked peanut allergy who are specifically sensitized to the basic subunit of Ara h 3 (11S globulin family). Conclusion That the dominant immunoreactivity in these patients is in a basic subunit of Ara h 3 was unexpected, because previous studies had indicated that Ara h 3 was only a minor peanut allergen and that the identified allergenic epitopes occurred mainly in the acidic Ara h 3 subunit.