Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.14.296442v1?rss=1 Authors: Schneider, M. M., Scheidt, T., Priddey, A. J., Xu, C. K., Hu, M., Devenish, S. R. A., Meisl, G., Dobson, C. M., Kosmoliaptsis, V., Knowles, T. P. J. Abstract: The detection and characterisation of antibodies in human blood is a key for clinical diagnostics and risk assessment for autoimmunity, infectious diseases and transplantation. Antibody titre derived from immunoassays is a commonly used measure for antibody response, but this metric does not resolve readily the two fundamental properties of antibodies in solution, namely their affinity and concentration. This difficulty originates from the fact that the fundamental parameters describing the binding interaction, affinity and ligand concentration, are convoluted into the titre measurement; moreover, the difficulty of controlling the surface concentration and activity of the immobilised ligand can make it challenging to distinguish between avidity and affinity. To address these challenges, we developed microfluidic antibody affinity profiling, an assay which allows the simultaneous determination of both affinity and antibody concentration, directly in solution, without surface immobilisation or antibody purification. We demonstrate these measurements in the context of alloantibody characterisation in organ transplantation, using complex patient sera, and quantify the concentration and affinity of alloantibodies against donor Human Leukocyte Antigens (HLA), an extensively used clinical biomarker to access the risk of allograft rejection. These results outline a path towards detection and in depth profiling of antibody response in patient sera. Copy rights belong to original authors. Visit the link for more info