Significance The diagnosis of many diseases is dependent upon accurate detection of particular antibodies present in blood. However, the development of biochemical reagents that can reliably detect these antibodies has proved remarkably challenging. This study describes a process to create biochemical reagents that can accurately and reliably detect disease-associated antibodies, without requiring knowledge of the cause or mechanisms of disease. Simultaneously, this process enabled identification of a critical environmental agent involved in celiac disease. Thus, the process presented here may enable the development of effective diagnostic tests for other medical conditions where such tests are lacking and the identification of environmental factors involved in disease.