What does a negative antinuclear antibody mean?

A negative antinuclear antibody test result indicates that there are no antinuclear antibodies. We know that if antinuclear antibodies are detected in the body, it often indicates that it has an important relationship with some autoimmune diseases. The most common one for women is systemic lupus erythematosus. Therefore, a negative antinuclear antibody test result is normal, indicating that there is no such disease. Antinuclear antibodies are also called anti-nucleic acid antigen antibodies, which have relatively important clinical significance in diagnosing diseases.

What are Antinuclear Antibodies

Antinuclear antibodies (ANA), also known as anti-nucleic acid antigen antibodies, are a group of autoantibodies produced against DNA, RNA, protein or molecular complexes of these substances in the cell nucleus. ANA can be distinguished according to the different properties of each molecule in its nucleus, such as: ① anti-DNA antibody; ② anti-histone antibody; ③ anti-non-histone antibody; ④ anti-nucleolus antibody, etc. Each major category is further divided into many types due to different antigenic characteristics. Therefore, ANA is a group of autoantibodies with different clinical significance in a broad sense, and a more accurate name should be the antinuclear antibody spectrum. ANA is mainly present in IgG, but is also found in IgM, IgA, and even IgD and IgE. Antinuclear antibodies can recognize various cell nuclear components and characteristically appear in many autoimmune diseases, especially rheumatic diseases. They can determine the activity and prognosis of the disease, observe treatment responses, and guide clinical treatment.

Clinical significance Antinuclear antibody examination is a screening test for autoimmune diseases. Antinuclear antibodies show varying degrees of positivity in a variety of autoimmune diseases, such as systemic lupus erythematosus (SLE, 95%-100%), rheumatoid arthritis (RA, 10%-20%), mixed connective tissue disease (MCTD, 80%-100%), Sjögren's syndrome (SjS, 10%-40%), systemic sclerosis (85%-90%), lupus hepatitis (95%-100%), primary biliary cirrhosis (95%-100%), etc. However, the positivity rate can be reduced after corticosteroid treatment.

About 20% to 50% of rheumatoid arthritis patients are IgG-type ANA positive. The positive rate of ANA in children with rheumatoid arthritis is about 19% to 35%. The positive rate is higher in those with iridocyclitis (50% to 90%). Therefore, a positive ANA indicates that rheumatoid arthritis may develop chronic cyclitis. It has been found that 75% of rheumatoid arthritis patients have polymorphonuclear leukocyte-specific ANA or anti-neutrophil cytoplasmic antibodies (ANCA) that can damage the leukocyte nucleus.

One autoimmune disease can detect multiple autoantibodies, and the detection of one antinuclear antibody may involve multiple related autoimmune diseases. Therefore, clinical physicians often need to refer to multiple immune indicators and make a comprehensive analysis based on clinical manifestations and other auxiliary examinations to make a diagnosis.