- Last Update On : 2012-12-23
Serologic tests for autoantibodies, including antinuclear antibodies (ANAs) and antibodies to specific nuclear antigens such as double-stranded DNA (dsDNA), play an important role in the diagnosis of systemic rheumatic diseases. However, test results for autoantibodies alone are insufficient to establish the diagnosis of a systemic rheumatic disease. No tests for autoantibodies should be performed without a clinical evaluation that leads to a presumptive diagnosis.
The original discovery of ANA was based on indirect immunofluorescence. Immunofluorescent antibody (IFA) is still the most commonly utilized method for detection of antinuclear antibodies. In this method, diluted patient serum is incubated on a slide containing a monolayer of human epithelial cells. If antibody is present, it binds to cell nuclei. After washing, bound antibody is detected by adding fluorescent anti-human IgG. Positive cells demonstrate bright green nuclear fluorescence with a distinct