Comparison between counterimmunoelectrophoresis and double radial immunodiffusion in the detection of antibodies to topoisomerase I in sera from scleroderma patients.

Sera from 146 patients with progressive systemic sclerosis have been submitted to the detection of anti-Scl 70 antibodies by both double radial immunodiffusion (ID) and counterimmunoelectrophoresis (CIE). CIE detected a significantly higher number of positive sera from patients with diffuse scleroderma, while no difference between the two techniques was noted in sera from patients with CREST variant. CIE increases the diagnostic importance of the serologic investigation in systemic sclerosis and gains a better distinction between subgroups of patients with different clinical expressions of this disease.