A novel engineered rabbit IgG Fc domain that eliminates human FcγR interactions for reduced background in antibody-based bioassays 9266

Abstract Description Rabbit IgG Fc amino acid sequences are highly similar to human IgG1 Fc, especially at the Fcγ receptor (FcγR) binding sites, and Biolayer Interferometry (BLI) kinetic analysis of rabbit IgG and human IgG1 showed equivalent interactions with human FcγRs. Recombinant Rabbit IgG antibody completely devoid of binding to human Fcγ can be used to reduce false positives caused by human Fcγ receptors in bioassays. We analyzed the rabbit Fc–human FcγR interface by antibody modeling and identified some novel mutations that disrupt the interface of IgGs and FcγRs. Rabbit IgG Fc domains can be engineered to contain a limited number of mutations such that human FcγR interactions are completely abolished while human FcRn interactions and rabbit Fc stability are unaffected. Here, we describe a mutated rabbit Fc region designed to significantly reduce potential non-specific antibody staining caused by IgG receptors in various applications, including flow cytometric analysis of human cells. Topic Categories Technological Innovations in Immunology (TECH)