title: Selective binding of heat- and antigen-aggregated IgG to Blue-Sepharose. Radioimmunoassay of circulating immune complexes.
abstract: In an attempt to find a direct method for the determination of circulating immune complexes in pathological sera we studied the ability of Cibacron Blue 3GA covalently bound to Sepharose 4B to bind heat- or antigen-aggregated human IgG. Blue-Sepharose was found to bind significant amounts of aggregated IgG (about 1.5 mg/ml packed gel) but very low amounts of monomeric IgG (about 0.1 mg/ml gel). The ability of Blue-Sepharose to bind immune complexes was tested on human pathological sera containing variable amounts of circulating immune complexes. Using both a turbidimetric measurement and Barkas' method we found that Blue-Sepharose is able to remove a very high percent of circulating immune complexes (greater than 80%) from sera. Considering the above observations a new method is described for the direct determination of circulating immune complexes using Blue-Sepharose as serum adsorbent and either 125I-labeled protein A or 125I-labeled rabbit IgG anti-human IgG to demonstrate the binding of immune complexes.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex / Q000032:analysis* / Q000378:metabolism; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D001798:Blood Proteins / Q000032:analysis; D006358:Hot Temperature; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods*; D012685:Sepharose / Q000031:analogs & derivatives*; D013205:Staphylococcal Protein A
chemical_list: D000936:Antigen-Antibody Complex; D001798:Blood Proteins; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; C029483:Blue-Sepharose; D012685:Sepharose