TagLite® two-cell assay - the next dimension to discovering new antibody drugs
Antibodies are central mediators of the immune system and, as such, are considered excellent candidates for the development of therapeutic drugs. As the complexity of these molecules increases, so does the demand for more rigorous assays to study them. In this webinar, we present a new two-cell binding assay developed by Roche Glycart, based on the TagLite® assay from Cisbio Bioassays. This assay enables the analysis of antigen binding on huFcγR binding, and can also potentially be extended to studying simultaneous target binding of bispecific molecules. Transfected Hek cells expressing huFcγRIIIa labeled with terbium (donor) are mixed with transfected Hek cells expressing antigen Y labeled with SNAP-Red (acceptor) and antibody X (Ab X) or its Fc-variant. Energy transfer to SNAP-Red can only take place if the antibody binds to both antigens Y and huFcγRIIIa. If the antibody binds to only one of the proteins, no emission from the acceptor can be detected, due to insufficient proximity between cells. The assay shows that, although binding of Ab X and its Fc-variant to the antigen is similar as expected, the Fc mutation completely abrogates FcγRIIIa binding, even when introducing the avidity effect by antigen binding. This new assay, established using Tecan´s Infinite® M1000 PRO microplate reader, opens up a new and exciting approach to studying protein-protein interactions in the drug discovery process.