title: Detection of IgG aggregates or immune complexes using solid-phase C1q and protein A-rich Staphylococcus aureus as an indicator system.
abstract: A radioimmunoassay for detection of C1q-binding IgG aggregates and antigen-IgG antibody complexes is described. The assay makes use of solid-phase C1q and 32p-labelled protein A-rich Staphylococcus aureus as an indicator system. Both 19S and heavier IgG aggregates that fixed C1q were detected. The sensitivity of the assay permitted detection of heavy (19-25S) IgG aggregates at a concentration of 8 mug/ml or less. The results indicated that detection of IgG in this assay is dependent on the degree of IgG polymerization and the molar ratio between the solid-phase C1q and the IgG polymers. Albumin-anti-albumin complexes, preformed at equilibrium with antibody to antigen molar ratios of 2:1 to 3:1 and at antigen concentrations of 25 to 40 mug/ml, were also detectable using the described radioimmunoassay.
mesh_terms: D000936:Antigen-Antibody Complex; D001426:Bacterial Proteins / Q000378:metabolism; D001666:Binding Sites, Antibody; D003172:Complement C1 / Q000378:metabolism; D003165:Complement System Proteins; D005557:Formaldehyde / Q000494:pharmacology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis* / Q000378:metabolism; D011108:Polymers; D011485:Protein Binding; D011863:Radioimmunoassay / Q000379:methods; D012709:Serum Albumin / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013211:Staphylococcus aureus / Q000276:immunology; D013997:Time Factors
chemical_list: D000936:Antigen-Antibody Complex; D001426:Bacterial Proteins; D003172:Complement C1; D007074:Immunoglobulin G; D011108:Polymers; D012709:Serum Albumin; D005557:Formaldehyde; D012710:Serum Albumin, Bovine; D003165:Complement System Proteins