According to the clinical significance of autoantibodies, they can be classified as follows: 1. Disease signature autoantibodies: These autoantibodies are only found in certain AIDs and rarely in other diseases, and are of great diagnostic value for AIDs, but are less diverse and less sensitive, such as anti-Sm antibodies in SLE (sensitivity 20%-30%), anti-ribosomal P protein (rRNP) antibodies (sensitivity (sensitivity 20%-30%), anti-proliferative cell nuclear antigen (PCNA) antibody (sensitivity only 2%-7%). 2.Disease-specific autoantibodies: These autoantibodies are highly sensitive in certain AIDs and can also be found in other diseases, but with low sensitivity, such as anti-double-stranded DNA (dsDNA) antibodies in SLE (sensitivity 70%-80% and specificity 90%-95% during the active phase), and also in diseases such as autoimmune hepatitis type 1 and mixed connective tissue diseases (sensitivity less than 10%). 3, disease-related autoantibodies: these autoantibodies are closely related to a certain AID, but they can also appear in other diseases, and their sensitivity is not low, such as anti-SSA antibodies and anti-SSB antibodies in primary dry syndrome (pSS), with a positive rate of 70% and 40%, respectively, which are of great significance for the diagnosis of pSS, but they also often appear in SLE, with a positive rate of 50% and 30%, respectively. 4.Disease nonspecific autoantibodies: These autoantibodies can be found in a variety of AIDs and are not specific for disease diagnosis, such as antinuclear antibodies (ANA), which are seen in a variety of connective tissue diseases and are used as screening tests for connective tissue diseases. 5. Physiological autoantibodies: Autoantibodies against their own antigens are often present in normal people. These autoantibodies are of low potency and are not sufficient to cause damage to their own tissues, but they can assist in the removal of aging and metamorphosis of their own components and play an immune self-stabilizing effect.