Autoantibody detection in scleroderma patients. Diagnostic and analytical performances of a new coupled particle light scattering immunoassay.

OBJECTIVE

We evaluated the diagnostic and analytical performance of the Coupled Particle Light Scattering technology applied to the detection of anti-topoisomerase I (anti-Scl70) and anti-CENP-B autoantibodies.

METHODS

The Scl70 antigen was obtained by recombinant DNA procedures using a prokaryotic expression system; CENP-B was a Baculovirus-expressed recombinant protein. Anti-centromere and anti-Scl70 antibodies were assayed in serum samples from 288 patients, of whom 123 had systemic sclerosis/scleroderma and 165 constituted the control groups (including patients with other connective tissue diseases, viral infections, Lyme disease, and healthy subjects).

RESULTS

The sensitivity was 98.8% (confidence interval, 96-101%) for anti-Scl70 and 100% (99.6-100%) for anti-CENP-B; the specificity was 99.0% (98-100%) and 100% (99.9-100%) for anti-Scl70 and anti-CENP-B, respectively. The intra-assay coefficient variations (CV) ranged from 3.8 to 9.2% for anti-Scl70, and from 2.8 to 8.0% for anti-CENP-B. Inter-assay CVs were 8.1 to 12.0% for anti-Scl70, and 4.7 to 10.5% for anti-CENP-B. In 3 patients, coexpression of both antibodies was observed.

CONCLUSION

The results of this study demonstrate that the light scattering technology is also applicable to the detection of autoantibodies to intracellular antigens for the diagnosis of autoimmune rheumatic diseases.