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The Antinuclear Antibody ScreenANA/DNA/RF SCREEN The relatively inexpensive ANA/DNA/RF Screen is useful in the differential diagnosis of many disease conditions. It is particularly useful in patients suspected of having an arthritic condition due to autoantibodies to nuclear protein. A positive test does not diagnose disease, but should be followed up with quantitative assays and further clinical evaluation. Human epithelial (HEp-2) cells and Crithidia luciliae are used as fixed substrates for the determination of reactive ANA (Antinuclear Antibody) and ds-DNA (anti-double stranded DNA) respectively. ANA will bind specifically to corresponding antigenic sites in the cell nuclei. ds-DNA will bind in the kinetoplast of C. luciliae. The tests are run simultaneously and reviewed by fluorescent microscopy. Positive samples may show any of the common ANA patterns either individually or in combination. The rheumatoid factor (RF) is often tested by a qualitative latex agglutination test. Rheumatoid factor is positive in many cases of autoimmune disease. All three tests (ANA, DNA, and RF) can be ordered in a screen panel.1, 2
Figure 12. Rim (Peripheral) pattern; mitotic cell: chromosome positive References 1. Nakamura RM, C.L. Peebles, D.P. Molden, and E.M. Tan. Advances in laboratory tests for Autoantibodies to nuclear antigens in systemic rheumatic diseases, Laboratory Med. 15:190-198, 1984. 2. Tan, E.M. et.al. Antinuclear antibodies (ANAs): Diagnostically Specific Immune Markers and clues toward the Understanding of Systemic Autoimmunity. Clin. Immunol. Immunopathol. 47:121-141, 1988. IGeneX, Inc. |
