Clinical Information

Antinuclear antibodies (ANAs) directed against a variety of macromolecules occur in extraordinarily high frequency in systemic rheumatic diseases. Although these antibodies were first associated with systemic lupus erythematosus (SLE), the list of implicated diseases has expanded and many rheumatic diseases are characterized by the presence of one or more of these ANAs. For instance, anti-SS-A/Ro and anti-SS-B/La antibodies are associated with SLE and Sjögren's Syndrome (SS), anti-dsDNA and anti-Sm antibodies with SLE, anti-histone antibodies with SLE and Drug Induced Lupus, anti-RNP antibodies with mixed connective tissue disease (MCTD) and SLE, anti-Scl-70 antibodies with scleroderma (progressive systemic sclerosis [PSS]), anti-Jo-1 antibodies with polymyositis and dermatomyositis and anti-centromere antibodies with CREST syndrome.

The Immunofluorescence assay (IFA) has been used as the standard method in the detection of ANAs. Although the IFA is a sensitive test, it is laborious when testing large numbers of patient samples and is subject to errors from human interpretation and from variability in fluorescent microscopes. The IFA HEp-2 ANA test is also subject to the following concerns: it is sometimes insensitive to certain sera containing antibodies to SS-A, SS-B, Sm, or dsDNA6 and it tends to find sera positive in a large number of patients who do not develop systemic rheumatic diseases within a follow-up two-year period. The Enzyme Immunoassay (EIA) test system is an excellent alternative to the IFA test system for screening patient's serum for the presence of ANAs of clinical significance. The EIA test system efficiently screens large numbers of patient samples and reduces human error.

The Bio-Rad Autoimmune EIA ANA Screening Test collectively detects, in one well, total ANAs against double stranded DNA (dsDNA, nDNA), histones, SS-A/Ro, SS-B/La, Sm, SmRNP, Scl-70, Jo-1, and centromeric antigens, along with sera positive for IFA HEp-2 ANAs. Sera positive on the EIA ANA Screening Test are further tested for the specific autoantibodies indicative of various systemic rheumatic diseases.