Human serum substitution by artificial sera of scalable allergen reactivity based on polyclonal antibodies and chimeras of human Fc[gamma]RI and IgE domains

Human sera are the first choice as controls for diagnostic applications such as immunoassays, but are limited regarding availability, varying quality, and high costs. In this study, we aimed to circumvent these limitations by the use of a chimeric adaptor molecule comprising the extracellular domains of the human Fc[gamma]RI (CD64) fused with human IgE Fc domains (CD64-IgE Fc). Allergen-specific antibodies were produced in rabbits using eight different allergens, extracts, and allergen mixtures including mites, pollen, drugs, and food. Preincubation of polyclonal IgG with CD64-IgE Fc established allergen-specific artificial sera that showed comparable results for more than 20 allergens and allergen extracts in three diagnostic systems for the determination of specific IgE. The agreement for these artificial sera is within ±1 radioallergosorbent test (RAST) class. Hence, rabbit IgG complexed with the IgG-specific CD64-IgE Fc adaptor molecule could provide a substitute for human reference sera with specificity for virtually any protein of interest.