Autoantibodies that react with various cellular constituents are widely detected in sera from patients with connective tissue diseases and rheumatic disormatic disorders. Therefore, they provide us useful informations for diagnosis,
classification
of
disease subsets and prediction of prognosis. Among these autoantibodies, antinuclear antibody (ANA) has been widely used. In addition, an attempt to classify rheumatic disease subsets by the analysis of the antibodies to extractable nuclear
antigen(ENA)
is being under way recently. In this paper, analysis of antibodies to ENA in the sera of anti-nuclear antibody positive patients was carried out to correlate the clinical diagnosis and ANA pattern. Four antibodies to ENA(anti-RNP, anti-Sm,
anti-SS-A/Ro
and anti-SS-B/La) in the sera of 140 ANA positive patients who visited Severance Hospital between March 1991 and Feruary 1993 were analyzed and the following results were obtained.
The positive rate of antibodies to ENA test was 40.0% (56 positive cases) in 140 ANA positive patients' sera. The occurrence of antibodies to ENA were in the orders of anti-SS-A/Ro 60.7%, anti-RNP 58.9%, anti-SS-B/La 30.4% and anti-Sm 17.9%. The
most
frequent (73.2%) ANA pattern in patients showing positive antibody reaction to antibodies to ENA were SLE(69.6%), neonatal lupus(3.6%), mixed connective tissue disease (MCTD, 7%). The most frequently observed antibody to ENA in patients with
anti-DNA
antibody was anti-SS-A/Ro 66.7%.
In conclusion, the combination of ANA and antibody test to ENA will provide us a useful tool for the diagnosis and subset classification of systemic rheumatic diseases.
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