The Antinuclear Antibodies Test - Research Paper Example

The Antinuclear Antibodies Test Antinuclear antibodies are autoantibodies that are produced by the immune system when it recognizes the body’s own cell’s nuclear components as foreign (Cassel & Rose, 2003). In simpler terms, autoantibodies directed against normal components of the cell nucleus are termed antinuclear antibodies (GPAC, 2007). These antibodies are often found in autoimmune diseases such as rheumatoid arthritis, systemic lupus erythmatosis (SLE), and polymyositis (Casse & Rose; Slater, Davis and Shmerling, 1996). The detection of these autoantibodies form the basis for the diagnosis of autoimmune diseases and the test performed for detecting these is called the ANA test. ANAs were discovered in the 1940s during the investigation of LE cell test for SLE (Lahita, 2004). Immunofluorescent ANA test using HEp-2 cells is believed to be the gold standard for autoantibody screening (Satoh, Mercado and Chan, 2009). ELISA is often the next step in screening of specific ANAs (Satoh, Mercado and Chan). In spite of the advancements in new methodologies and tests for the detection of ANAs, there is still a considerable lack of sensitivity in their detection and inaccuracies such as false positives and false negatives are common (Meroni & Ferrari, 2010). Uses of the ANA Test Autoantibodies are considered the “serologic hallmark” of autoimmune rheumatic diseases (Fritzler, 2011, p. 19). The ANA test is used for screening and diagnosis of systemic ARDs (Hirschfield & Heathcoate, 2011). A positive ANA test is reported in 95% of the patients with SLE, 40-70% in those with Sjogren’s syndrome, 60-70% in those with systemic sclerosis, 30-80% in those with idiopathic inflammatory myositosis, and almost 100% in those with disorders of the connective tissue (Hirschfield & Heathcoate). ANA tests are now in routine use for both the diagnosis as well as follow-up of patients with systemic ARDs (Satoh, Mercado, and Chan, 2009). The ANA test is of great utility in diagnostic testing of autoimmune diseases of the liver, especially in transplant cases (Hirschfield & Heathcoate). However, since the ANA test reports are often positive for other non-autoimmune conditions, it is often used in conjunction with other screening tests (Chudwin et al., 1983). Techniques used for ANA test The indirect immunofluorescence assay (IIF) using HEp-2 cells, also called the ANA-HEp-2 test, is the standard test for detection of antinuclear antibodies (Mariz et al., 2011). HEp-2 cells have about 100-150 autoantigens and the pattern and the titer can indicate a variety of antigens (ACR, 2011). The ANA-HEp-2 test is performed by placing the patient’s serum on a layer of HEp-2 cells on a microscope slide (Lehman, 2004). The slide is then washed off to remove the serum and a specific labeled antibody is added. If antinuclear antibodies are present, the labeled antibody attached to the autoantibody will glow under fluorescent light, indicating a positive result (Lehman). However, at a 1:80 dilution, a positive ANA-HEp-2 test is reported in about 13.3% healthy individuals with no evidence of an autoimmune condition (Mariz et al.). Therefore, in absence of clinical indication for ARD, ANA is generally not tested, since a positive ANA report in absence of clinical symptoms for ARD is of low diagnostic utility (Marin et al., 2009). Chen et al. (1992) showed that the use of streptavidin-biotin-peroxidase complex technique using streptavidin-biotin-peroxidase complex on HEp-2 cells has better specificity than IIF for the detection of ANA. However, this technique failed to emerge as the standard test due to several limitations. Several other techniques are widely prevalent for the detection of ANAs. These include specific tests for anti-dsDNA autoantibodies, antihistone autoantibodies, anti–Ro (SS-A) and anti–La (SS-B) autoantibodies, anti-Sm and anti-nRNP autoantibodies, anti–Scl-70 autoantibodies, anticentromere autoantibodies, and antinucleolar autoantibodies (Kavanaugh et al. 2000). Positive fluorescence staining is also helpful in the detection of ANA, but the precise identification of the autoantibodies is not possible (Peene et al. 2001). To identify specific autoantibodies, additional tests using western immunoblotting, ELISA, immunoprecipitation, and line assay are performed (Peene et al.). The anti-Sm and anti-dsDNA antibodies are associated with SLE, anti-Jo-1 antibodies are specifically associated with polymyositis, anticentromere and anti-Scl70 antibodies are specifically associated with systemic sclerosis, anti-SSA and anti-SSB antibodies are specifically associated with Sjögren's syndrome, rheumatoid arthritis, lupus, and scleroderma (Peene et al.). Anti-RNP antibodies are found to be specifically associated with mixed connective tissue disease (Peene et al.). Relationship between ANA Test and Autoimmune Diseases The various autoimmune diseases associated with ANA and their corresponding test specificity is discussed as follows: Systemic Lupus Erythematosus (SLE) – This autoimmune disease involves the hematopoietic system and multiple organs including the skin, lungs, kidney, etc, apart from joints, serous membranes, and the central nervous system (Okesenberg & Brassat, 2006). The disease has several manifestations that affect cardiac, dermatologic, neurologic, vascular, renal and other systems (Okesenberg & Brassat). Anti-Sm and anti-dsDNA antibody tests are performed for this disease. The positive ANA specificity for SLE is 93% (Lahita, 2004). Polymyositis/dermatomyositis – Polymyositis is a systemic idiopathic inflammatory autoimmune disease, which results in skeletal muscle inflammation (Torre, Lamb and Ruiswyk, 2008). Dermatomyositis is also associated with skeletal muscle inflammation (Torre, Lamb and Ruiswyk). The anti-Jo-1 antibody tests are performed for this disease. The positive ANA specificity for this disease is 61% (Lahita, 2004). Scleroderma – This condition is characterized by fibrosis and thickening of the skin and is believed to be mediated by lymphocytes (Torre, Lamb and Ruiswyk, 2008). Anticentromere and anti-Scl70 antibody tests are performed for this disease. The positive ANA specificity for scleroderma is 85% (Lahita, 2004). Sjögren's syndrome (SS) – This autoimmune disease is associated with exocrine gland inflammation, especially the salivary and lacrimal glands (Ramos-Casals, Stone, and Moutsopoulos, 2012). The anti-SSA and anti-SSB antibody tests are performed for this syndrome. The positive ANA specificity for scleroderma is 48% (Lahita, 2004). Rheumatoid arthritis (RA) – This is a progressive inflammatory disease associated with synovial membrane proliferation along with polyarthritis in joints (Cush, Weinblatt and Kavanaugh, 2010). Anti-SSA and anti-SSB antibody tests are performed for this disease. The positive ANA specificity for RA is 41% (Lahita, 2004). Autoimmune Hepatitis – Autoimmune hepatitis is an inflammatory disease of the liver and is considered as a putative autoimmune disease as it shares some features with other autoimmune diseases (Hirschfield and Heathcote, 2011). The positive ANA specificity for autoimmune hepatitis is 71% (Lahita, 2004). References ACR. (2011). Methodology of Testing for Antinuclear Antibodies. American College of Rheumatology. Retrieved from http://www.rheumatology.org/practice/clinical/position/ana_position_stmt.pdf. Cassel, D. K., & Rose, N. R. (2003). The Encyclopedia of Autoimmune Diseases. New York: Infobase Publishing. Chen, R. Y.L., Kei•lam, W., Lawton, J. W. M., & Ho, F. C. S. (1992). Antinuclear Antibody Detection Using Streptavidin-Biotin-Peroxidase Complex on HEp-2 Cell Substrate. Asian Pacific Journal of Allergy and Immunology, 10 (1), 19-24. Chudwin, D. S., Ammann, A. J., Cowan, M. J., & Wara, D. W. (1983). Significance of a Positive Antinuclear Antibody Test in a Pediatric Population. Archives of Pediatric and Adolescent Medicine, 137 (11), 1103-1106. Cush, J. J., Weinblatt, M. E., and Kavanaugh, A. (2010). Rheumatoid Arthritis: Early Diagnosis and Treatment. New York: Professional Communications. Fritzler, M. J. (2011). The antinuclear antibody test: Last or lasting gasp. Arthritis & Rheumatism, 63 (1), 19-22. GPAC. (2007, April 1). Antinuclear Antibody (ANA) Testing for Connective Tissue Disease. Retrieved from http://www.bcguidelines.ca/pdf/ana.pdf. Hirschfield, G., & Heathcoate, E. J. (2011). Autoimmune Hepatitis: A Guide for Practicing Clinicians. Ontario: Springer. Kavanaugh, A., Tomar, R., Reveille, J., Solomon, D. H., & Homburger, H. A. (2000). Guidelines for Clinical Use of the Antinuclear Antibody Test and Tests for Specific Autoantibodies to Nuclear Antigens. Archives of Pathology & Laboratory Medicine, 124, 71-81. Lahita, R. G. (2004). Systemic Lupus Erythematosus.California: Academic Press. Lehman, T. J. A. (2004). It's Not Just Growing Pains: A Guide to Childhood Muscle, Bone, and Joint Pain, Rheumatic Diseases, and the Latest Treatments. New York: Oxford University Press. Marin, G. G., Cardiel, M. H., Cornejo, H., & Viveros, M. E. (2009). Prevalence of Antinuclear Antibodies in 3 Groups of Healthy Individuals: Blood Donors, Hospital Personnel, and Relatives of Patients With Autoimmune Diseases. Journal of Clinical Rheumatology, 15 (7), 325-329. Mariz, H. A., Sato, E. I., Barbosa, S. H., Rodrigues, S. H., Dellavance, A., & Andrade, L. E. C. (2011). Pattern on the Antinuclear Antibody–HEp-2 Test Is a Critical Parameter for Discriminating Antinuclear Antibody–Positive Healthy Individuals and Patients With Autoimmune Rheumatic Diseases. Arthritis & Rheumatism, 63, 191-200. Meroni, P. L., & Schur, P. H. (2010). ANA screening: an old test with new recommendations. Annals of Rheumatic Diseases, 69, 1420-1422. Okesenberg, J., & Brassat, D. (2006). Immunogenetics of Autoimmune Disease. New York: Springer. Peene, I., Meheus, L., Veys, E. M., & Keyser, F. D. (2001). Detection and identification of antinuclear antibodies (ANA) in a large and consecutive cohort of serum samples referred for ANA testing. Annals of Rheumatic Diseases, 60, 1131-1136. Ramos-Casals, M., Stone, J. H., and Moutsopoulos, H. M. (2012). Sjögren's Syndrome: Diagnosis and Therapeutics. London: Springer. Satoh, M., Mercado, M. V., & Chan, E. K. L. (2009). Clinical interpretation of antinuclear antibody tests in systemic rheumatic diseases. 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