Tracking humoral responses using self assembling protein microarrays

The humoral immune response is a highly specific and adaptive sensor for changes in the body's protein milieu, which responds to novel structures of both foreign and self antigens. Although Igs represent a major component of human serum and are vital to survival, little is known about the response specificity and determinants that govern the human immunome. Historically, antigen‐specific humoral immunity has been investigated using individually produced and purified target proteins, a labor‐intensive process that has limited the number of antigens that have been studied. Here, we present the development of methods for applying self‐assembling protein microarrays and a related method for producing 96‐well formatted macroarrays for monitoring the humoral response at the proteome scale. Using plasmids encoding full‐length cDNAs for over 850 human proteins and 1700 pathogen proteins, we demonstrate that these microarrays are highly sensitive, specific, reproducible, and can simultaneously measure immunity to thousands of proteins without a priori protein purification. Using this approach, we demonstrate the detection of humoral immunity to known and novel self‐antigens, cancer antigens, autoimmune antigens, as well as pathogen‐derived antigens. This represents a powerful and versatile tool for monitoring the immunome in health and disease.