Deciphering the Antibodyome - Peptide Arrays for Serum Antibody Biomarker Diagnostics

The analysis of antibodies in human serum is an established technique in the laboratory diagnosis of infectious as well as autoimmune diseases. The multitude of antibody reactions towards pathogens and likewise the antibody profile in autoimmune diseases does contain a wealth of proteomic (antibody) data that may constitute valuable diagnostic information with relevance for the patient's prognosis and response to therapy. Hence the use of antibodies as diagnostic biomarkers may be one of the most promising strategies to identify patient subgroups. The presence or absence of antibodies directed against specific epitopes could represent a serologic biomarker that is able to predict the severity of a disease and assist in medical decision making. In addition, parallel detection of many different antibodies in a serum sample would be of great value in many areas of basic immunological research. Peptide arrays displaying biologically active small synthetic peptides in either low, medium or high-density formats represent an attractive technology to probe complex serum samples for the presence of such antibody analytes. Holding the unique capacity to break down the heterogeneous immunologic response into monoclonal antibody specificities and to differentiate subtle changes in antibody abundance and specificity, the peptide array technology by far extends the diagnostic potential of any conventional serologic assay. Together with an unrivalled parallelity, peptide (micro)array analysis opens new perspectives for the novel use of antibodies as diagnostic biomarkers and provides unique access to a more differentiated serological diagnosis. This review recapitulates the development of the peptide array technology with a focus on recent advances and current state of the art platforms for antibody diagnostics. Latest applications of peptide arrays for the serologic diagnosis of infectious diseases, autoimmunity and allergy are discussed, and conclusions for future developments and implications are drawn.