The disclosed embodiments concern methods, devices, and systems for identifying candidate biomarkers useful for the diagnosis, prognosis, monitoring and screening and/or as targets for the treatment of diseases and conditions in subjects, in particular autoimmune and infectious diseases. The identification of candidate biomarkers is predicated on identifying discriminating peptides present on a peptide array, which can distinguish samples from different subjects having different health conditions by the binding patterns of antibodies present in the samples.