title: Hepatitis B circulating immune complexes. Characterization by radioimmunoprecipitation--PEG assay (RIPEGA).
abstract: Incidence of circulating immune complexes (IC) was investigated in carriers of hepatitis B antigen (HBAg) and/or anti-HB antibodies (anti-HBAb). Three methods were used: radiolabelled C1q binding test (C1qBT), complement fixation test (CFT), and optical density (OD) measurement after dissolution of 3% polyethylene glycol (PEG) precipitate of serum. A highly significant correlation was obtained between these three techniques. The level of IC was higher in carriers of HBAg without anti-HBAb, than in others. The characterization of HBAg and anti-HBAB in IC was carried out by a new procedure, the radioimmunoprecipitation-PEG assay (RIPEGA), This sensitive and reproducible test was performed by incubation of 125I-HBAg or 125I-HBAG with 3% precipitate of the carriers' sera. Separation of free from complexed 125I-HBAg or 125I-HBAb was achieved by PEG precipitation. A highly significant correlation was found between the levels of circulating IC evaluated by the C1q-BT and the quantities of HBAg or anti HBAb measured by RIPEGA. RIPEGA was used to quantify HBAg and anti-HBAb present in serum from HBAg and/or anti-HBAb carriers, confirmed by a radioimmunoassay. In preliminary results, RIPEGA was shown to be more sensitive than classical radioimmunoassay.
mesh_terms: D000906:Antibodies; D000936:Antigen-Antibody Complex; D002353:Carrier State / Q000276:immunology; D006509:Hepatitis B / Q000276:immunology*; D006511:Hepatitis B Antigens / Q000032:analysis*; D006801:Humans; D011092:Polyethylene Glycols; D011863:Radioimmunoassay / Q000379:methods*
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D006511:Hepatitis B Antigens; D011092:Polyethylene Glycols