Production of Native Bispecific Antibodies in Rabbits

BACKGROUND: A natural bispecific antibody, which can be produced by exchanging Fab arms of two IgG4 molecules, was first described in allergic patients receiving therapeutic injections with two distinct allergens. However, no information has been published on the production of natural bispecific antibody in animals. Even more important, establishment of an animal model is a useful approach to investigate and characterize the naturally occurring antibody. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrated that a natural bispecific antibody can also be generated in New Zealand white rabbits by immunization with synthesized conjugates. These antibodies showed bispecificity to the components that were simultaneously used to immunize the animals. We observed a trend in our test animals that female rabbits exhibited stronger bispecific antibody responses than males. The bispecific antibody was monomeric and primarily belonged to immunoglobulin (Ig) G. Moreover, bispecific antibodies were demonstrated by mixing 2 purified monospecific antibodies in vivo and in vitro. CONCLUSIONS/SIGNIFICANCE: Our results extend the context of natural bispecific antibodies on the basis of bispecific IgG4, and may provide insights into the exploration of native bispecific antibodies in immunological diseases.