Protein microarray is a highly sensitive tool for antibody detection in serum. Monitoring of patients’ antibody titers to specifi c antigens is increasingly employed in the diagnosis of several conditions, ranging from infectious diseases, allergies, autoimmune diseases, and cancer. In this protocol we present a detailed
method for enzymatic generation of disease-specifi c O- glycopeptides and how to monitor the antibody response to these in serum using microarray technology.