ANCA assays are generally divided into indirect immunofluorescence assays and other assays for autoantibodies to target antigens, such as ELISA. Indirect immunofluorescence, if positive, is common in granulomatous vasculitis, microscopic polyangiitis, etc. It can also be found in autoimmune diseases such as inflammatory bowel disease, rheumatoid arthritis, autoimmune liver disease and systemic lupus erythematosus, and may also be positive for ANCA in infectious diseases, lymphoma and after the use of certain drugs. If the indirect immunofluorescence method is positive, ELISA will be recommended to detect the target antigen, and it is best to combine the two methods, the specific results should be combined with the patient’s clinical symptoms and other test results, the doctor to make a comprehensive judgment. Since its discovery in 1982, it has been widely used as a major serologic marker for systemic vasculitis.