Immunoglobulins comprise 30-50% of human plasma proteins, and can show several- fold increased levels in many diseases. "Natural" autoantibodies, presumably part of an immune homeostasis mechanism, may comprise >50% of a healthy individual's plasma. The differential identification of disease-associated antibodies must therefore be able to effectively subtract a large and idiosyncratic "background" component. Although autoantibodies and disease are important and well-studied, much work remains to be done in this area, which involves many diseases and potential applications. Proteomics researchers are increasingly involved in generating reliable reagents and in sharing them. This project will deliver a novel research tool for autoantibody and autoantigen biomarker discovery, to be provided for the scientific research community as a kit that incorporates Differential Capture Proteomics technology to subtract non disease-specific binding. This versatile kit will integrate proven modular and existing kit components with innovative methodologies, and will provide an experimentally straightforward but powerful tool to explore a wide range of antibody and antigen biomarker discovery projects. The Autoantibody and Autoantigen Biomarker Discovery Kit will therefore be offered to the Research Community in the hope that a two-way flow of ideas and reagents may contribute to such efforts in a variety of diseases involving autoantibodies. Specific Aim 1: Develop Kit Component 1, to isolate phage peptides binding disease-associated antibodies Specific Aim 2: Develop Kit Component 2, to isolate peptide beads binding disease-associated antibodies Specific Aim 3: Develop Kit Component 3, to isolate antibody beads binding disease-associated antigens PUBLIC HEALTH RELEVANCE: Although autoantibodies and disease are important and well-studied, much work remains to be done in this area, which involves many diseases and potential applications. This project will deliver a novel research tool for autoantibody and autoantigen biomarker discovery, to be provided for the scientific research community as a kit that incorporates Differential Capture Proteomics technology to subtract non disease-specific binding.