The antinuclear antibody (ANA) test is used as a primary test to help evaluate a person for autoimmune disorders that affect many tissues and organs throughout the body and is most often used as one of the tests to help diagnose systemic lupus erythematosus (SLE). ANA are a group of auto antibodies produced by a person's immune system when it fails to adequately distinguish between 'self' and 'nonself'. They target substances found in the nucleus of a cell and cause organ and tissue damage. ANA testing may be used along with or followed by other autoantibody tests.