We have constructed and expressed a fusion protein consisting of the major peanut allergen
Ara h 2 plus the hinge, CH2, and CH3 regions of human IgG1. Western blotting confirmed
that AHG2 had the predicted size of 44 kDa (Fig 2, A). The amino acid sequence of AHG2
was confirmed by using mass spectrometry. Further probing found that AHG2 was
recognized by both monoclonal anti–Ara h 2 and anti-human IgG Fc–specific antibodies
(Fig 2, A). In addition, the ELISA or Western blot result showed that the peanut allergen
Ara h 2 component of AHG2 was recognized by peanut-specific IgE (Fig 2, B, and see Fig
E1 in this article’s Online Repository at www.jacionline.org). Flow cytometry showed that
AHG2 binds to FcγRIIb expressed on HMC-1 cells (Fig 2, C). These results demonstrate
that the fusion protein AHG2 was expressed properly, having both peanut allergen and Fcγ
antigenic or functional moieties intact.