Diagnostic immunological methods in oral mucosal diseases

Summary Pemphigus and pemphigoid are rare, debilitating disorders that cause painful blisters of the skin and/or mucous membranes, including inside the mouth and nose. They are autoimmune diseases, which means that the body's immune system produces proteins called autoantibodies that wrongly target normal parts of the body. There are several different types of both diseases and among them, pemphigus vulgaris, paraneoplastic pemphigus, mucous membrane pemphigoid, linear IgA disease and lichen planus pemphigoides are the common diseases that involve oral mucosa (the skin inside the mouth). These diseases affect people's quality of life and can even threaten lives. Sometimes the symptoms can be similar to other diseases such as oral lichen planus and discoid lupus erythematosus, and a variety of methods can be used to help diagnosis. These include direct and indirect immunofluorescence, salt‐split skin test, biochemical tests (enzyme‐linked immunosorbent assay, immunoblotting and immunoprecipitation), as well as an emerging technology called protein microarrays. The authors from China reviewed and compared the above methods for diagnosing autoimmune blistering diseases, oral lichen planus and discoid lupus erythematosus involving oral mucosa. Remarkably, these immunological techniques not only help with diagnosis, but can also be used to identify disease‐related target antigens and autoantibodies in the blood, for the study of their relevance to development of diseases, clinical manifestation (symptoms), severity of diseases, concomitant diseases (other diseases occurring at the same time), and influence on treatment and prognosis. The above methods are beneficial for study, and help clinicians make individualized treatment regimens and evaluate patients’ prognosis.