Antinuclear antibody

Antinuclear antibody (ANA) is a type of autoantibody that has the capability to bind certain structures within the nucleus of the cells. The ANA test is a significant tool for diagnosing autoimmune diseases, and is most often used to detect systemic lupus erythematosus (SLE).

Overview

The term "antinuclear" refers to the fact that these antibodies react against the cell nucleus. They are produced by the immune system when it fails to adequately distinguish between "self" and "non-self". The exact reason for this failure is unknown, but it is often associated with autoimmune diseases.

Antinuclear Antibody Test

The antinuclear antibody test is a blood test used to measure the amount and pattern of antibodies in the blood. It is used to detect diseases characterized by autoimmunity. This test is often used when a patient shows signs and symptoms of an autoimmune disease but lacks definitive diagnostic criteria.

Clinical Significance

The presence of ANAs in a patient's blood can indicate an autoimmune disease, such as rheumatoid arthritis, systemic lupus erythematosus, or Sjögren's syndrome. However, ANAs can also be present in individuals with other conditions or even in healthy individuals, particularly the elderly. Therefore, a positive ANA test alone is not sufficient to diagnose an autoimmune disease.

Types of Antinuclear Antibodies

There are several different types of ANAs, each associated with different diseases. These include:

• Anti-SSA/Ro and Anti-SSB/La antibodies: These are often found in patients with Sjögren's syndrome or lupus.
• Anti-Sm antibodies: These are strongly associated with lupus.
• Anti-Scl-70 antibodies: These are often found in patients with scleroderma.
• Anti-Jo-1 antibodies: These are associated with a condition called polymyositis.

See Also

• Autoimmune disease
• Autoantibody
• Systemic lupus erythematosus
• Rheumatoid arthritis
• Sjögren's syndrome