IMMUNOLOGY
PAGE EXPIRES: June 2000
SYNONYMS: ANA, ANF, FANA
COMPONENT TESTS: None (single test)
SCHEDULE: Reference Lab Turnaround time: 10 working days
SPECIMEN AND COLLECTION REQUIREMENTS:
CAUSES FOR REJECTION: Improperly labeled specimen; hemolysis, lipemia, or turbidity
STORAGE AND SHIPPING: Refrigerate at 4° C
USES: The IFA-ANA test is positive in virtually all patients with a clinical diagnosis of Systemic Lupus Erythematosus (SLE) even when the LE-cell test is negative. Therefore the greatest value of the IFA-ANA test is that a negative result essentially excludes a diagnosis of active SLE (highly sensitive). Anti-nuclear antibodies are often associated with other autoimmune disorders such as Rheumatoid Arthritis, Systemic Sclerosis, Sjogren's Syndrome, Polymyositis and liver disease.
NORMAL VALUES: Titer < 1:20
NOTE: All positive titers of 1:40 will automatically have an anti-DNA performed
METHOD: Indirect immunofluorescence
DESCRIPTION AND COMMENTS: The indirect immunofluorescent antibody (IFA) test is the most widely employed method of detecting anti-nuclear antibodies (ANA). Although the ANA titer may not correlate with the clinical course of the disease in all cases, most SLE patients produce high ANA titers with homogeneous and peripheral staining patterns. In addition, speckled, and nucleolar staining patterns may be associated with SLE at lower frequencies.
False positives may occur in numerous immunologically related diseases including pernicious anemia, chronic active hepatitis, and other collagen diseases. Numerous commonly prescribed drugs are known to induce a "lupoid" condition with elevated ANA titers. Caution is strongly advised in interpreting ANA levels in patients on drug therapy. False negatives may occur during steroid and immunosuppressive therapy.
Indirect immunofluorescence is the method of choice for screening and quantitation of ANA. Commercially available human epithelial (HEp-2) cells fixed on slides are the substrate for which ANAs bind to epitopes within the nuclei of cells. The nature of this binding produces the ANA interpretative patterns.