scope:

The ANAs are associated with many immunologic disorders; however, they are the essential hallmark of systemic rheumatic diseases.

The significance of ANAs is as follows:

• Useful for screening and diagnostic evaluation of systemic rheumatic diseases. A negative test result is helpful in ruling out the possibility of SLE.

•  Some of these diseases have distinct profiles of ANA. Significant changes in the levels of certain specific ANA, such as antibodies to ds-DNA, are useful in following the causes of the diseases and their • responses to therapy. Levels of ANA do not necessarily correlate with severity of disease or response to therapy.

• ANAs can be useful as experimental reagents in the isolation of nuclear antigens, especially nonhistone antigens or in basic studies in cell biology.

Indirect immunofluorescence and immunoenzyme tests were commonly used for ANA screening, because these procedures are practical, sensitive, primary antigen-antibody reactions. Since 1996, advances in technology have provided new approaches to improve the accuracy and specificity in detection methods. Many laboratories now use enzyme-linked immunosorbent assays (ELISA) and other newly developed immunological tests that have been demonstrated to be suitable as preliminary screening tests to identify antinuclear antibodies. Differences in the data set derived from these assays may modify the interpretation of assay results; therefore, quality assurance information for ELISA-specific methods is included.