Measurement of Autoantibodies by ELISA Kits / 대한임상병리학회지

ABSTRACT

BACKGROUND: The detection of specific autoantibodies in the sera of patients with systemic rheumatic diseases plays a key role in the differential diagnosis. Enzyme-linked immunosorbent assays (ELISA) is known as sensitive and semiquantitative method to detect autoantibodies and ELISA kits using a recombinant fusion protein as antigen have been developed. So, various commercial ELISA have recently become available in a diagnostic laboratory. We investigated the clinical value of antinuclear autoantibodies using commercial ELISA kits. METHODS: The serum of 90 patients were tested for autoantibodies to SSA/Ro, SSB/La, nRNP/Sm and Sm antigens by ELISA using four commercial kits, EL-ANA(TM) (TheraTest, IL, USA), DIASTAT(TM)(SHIELD, DUNDEE, UK), QUANTALit(TM) (INOVA, CA, USA), Varelisa(TM) (elias, WI, USA). We evaluated the clinical usefulness of panel test of Varelisa(TM) in the diagnosis of systemic rheumatic diseases. RESULTS: The concordance rates of four ELISA kits for autoantibodies to SSA/Ro, SSB/La, RNP/Sm and Sm antigens were 83.6%, 74.5%, 87.5% and 80.0%, respectively. Using panel test of Varelisa(TM), positive rates of autoantibodies to Ul-snRNP, nRNP/Sm, Sm, SSA/Ro, SSB/La, Scl-70, CENP and Jo-1 antigens in SLE were 30.0, 40.0, 33.3, 46.7, 20.0, 20.0, 10.0, and 0%, respectively. Of 30 patients with SLE, 16 (53.3%) were positive for 2 or more antibodies. CONCLUSIONS: EL-ANA(TM), QUANTALite(TM) and Varelisa(TM) show more positive rates than DIASTAT(TM). The difference in the positive rates among four commercial ELISA kits may come from the different antigen sources. The panel test of 8 autoantibodies using Varelisa(TM) ELISA kit offers discriminative power and enhances the specificity of the assay in patients who lack clear evidence of clinically definite autoimmune disease.