The Ratio of Immunogenicity: A novel metric to rank the relative strength of an individual antigen’s capacity to stimulate an antigen-specific IgG response 2351

Abstract Description Despite significant efforts to identify targetable, immunogenic antigens in vitro, variability in population wide immune responses, combined with our inability to rank the relative immunogenicity of individual antigens, has led to frequent failures in validating predicted candidates in vivo. Recently, in an animal model of biomaterial biocompatibility, we observed that only ∼3% of residual antigens induced a graft-specific IgG-response ∼30% as strong as native tissue. Leveraging an optimized, shotgun immunoproteomics pipeline, we identified and quantified the magnitude of response toward each, individual, xeno-antigen present in this in vivo model. Additionally, we quantify the abundance (i.e. dose) of each antigen, within native tissue vs. the antigen removed biomaterial. By combining data on the strength of the residual immune response with the dose of each antigen, we developed and validated the Ratio of Immunogenicity (ROI; % residual response/% residual abundance), a novel and quantitative metric which can rank the relative immunogenicity of all antigens in an in vivo system. The ROI metric reveals that inherent properties (i.e., independent of dose) of individual antigens modulate their immune stimulatory capacity, from highly (i.e. strong) to minimally (i.e. weak) antigenic. The ROI is a new tool, with broad utility, which can identify highly immunogenic target antigens, and offers insight into basic immune biology and guiding developments to enhance clinical practice. Funding Sources Supported by R01HL153098 & the Mayo Clinic Foundation for Medical Research Topic Categories Technological Innovations in Immunology (TECH)