Changes in circulating immune complexes in tumour patient serum after in vitro or ex vivo affinity chromatography of blood plasma or whole blood over immunoglobulin-binding staphylococcal protein A-Sepharose.
Circulating immune complexes (CIC) were determined in tumour patient sera using three methods. One is based on PEG-precipitation, one on C1q-reactivity, and one on protein A-reactivity. About 25-30% of the sera were positive in at least one of the tests. Incubation of serum with protein A-Sepharose in vitro removed PEG-precipitable CIC from most sera, whereas C1q-reactive CICs had a much lower affinity to protein A. The protein A-reactive complexes showed considerable variation in their binding to protein A-Sepharose, and in some sera the amount of these CICs was actually increased. Similar changes in protein A-reactive CIC were also found during ex vivo treatment of tumour patients with immune adsorption. It is proposed that the binding of immune complexes to protein A can result in remodelling of protein A itself. Results from ultracentrifugation and fractionated PEG-precipitation support this hypothesis.
D000936:Antigen-Antibody Complex / Q000032:analysis*; D001769:Blood; D002846:Chromatography, Affinity; D003166:Complement Activating Enzymes; D015922:Complement C1q; D005590:Fractional Precipitation; D006801:Humans; D007163:Immunosorbent Techniques; D009369:Neoplasms / Q000276:immunology* / Q000628:therapy; D010956:Plasmapheresis; D012685:Sepharose; D013205:Staphylococcal Protein A
D000936:Antigen-Antibody Complex; D013205:Staphylococcal Protein A; D015922:Complement C1q; D012685:Sepharose; D003166:Complement Activating Enzymes