Generating allergen-specific human IgEs for immunoassays by employing human ε gene knockin mice

Antigen-specific human IgEs are important reagents in immunoassays to quantify antigen-specific IgEs in allergic patients, but they are not easy to prepare.

We constructed a knockin homozygous mouse strain, referred to as HεκKI strain, whose gene segment encoding γ1 constant region has been replaced by that encoding human ε constant region and gene segment encoding κ constant region replaced by that encoding human κ constant region. The mice were tested for their ability to produce antigen-specific chimeric human IgE (with mouse variable regions) upon the immunization with ovalbumin and papain. Subsequently, the spleen cells from the immunized mice were used as the source of B cells for the preparation of hybridomas, which secreted monoclonal human IgE antibodies specific for the antigens.

The HεκKI mice expressed human IgE (ε, κ) in serum at levels 10- to 30-fold higher than those of mouse IgE. Upon immunization with an antigen, the mice yielded splenic B cells for preparing hybridomas that secrete chimeric human IgE specific for the antigen. Purified IgEs from those hybridomas could activate a basophilic cell line to undergo degranulation upon the stimulation with their respective antigens.

We have developed a human ε gene and κ gene knockin mouse strain, which is useful for producing various antigen-specific chimeric human IgEs for potential use as standards in immunoassays.