The use of the radioimmunoprecipitation-PEG assay (RIPEGA) to detect anti-IgG antibodies.

A new procedure, the radioimmunoprecipitation--P.E.G. assay (RIPEGA) is proposed for the detection of anti-IgG antibodies (anti-IgG Ab). This sensitive and reproducible test was performed by incubation of radio-labelled human IgG (125I-IgG) with patient's sera. Separation of free from complexed 125I-IgG was achieved by a 7% P.E.G. precipitation. Preliminary results demonstrated anti-IgG Ab in 84.4% of the cases of sero-positive rheumatoid arthritis (R.A.), 85% of seronegative R.A., 43% of other forms of inflammatory arthritis, 50% of unclassified arthritis and in 10.5% of the control subjects.