Perfusion of canine serum over Staphylococcus aureus Cowan 1: Evidence for release of protein A and changes in specific antibody activity.

Abstract

Sera from three normal dogs were assessed for levels of Clq binding IgG and complement consumption after perfusion over Staphylococcus aureus Cowan I (SAC). Increased levels of Clq binding IgG were detected after perfusion of sera over SAC and were associated with complement consumption. Canine antiserum to human erythrocytes were also perfused over SAC and assessed for Clq binding IgG and hemolytic activity. Increased levels of Clq binding IgG in post-perfusion samples were detected which were associated with a decrease in hemolytic activity. IgG was determined to be present in molecular weight fractions greater than 200,000 M.W. in post-perfusion chromatographically fractionated sera. Moreover, 5% polyethylene glycol (PEG) precipitated IgG from post-perfusion sera was functional in antibody dependent cellular cytotoxicity assays. Putative staphylococcal protein A isolated from post-perfusion sera produced a precipitin band in double diffusion agarose gel studies when reacted with normal human and canine sera. A polypeptide co-migrating with purified protein A could be detected by polyacrylamide gel electrophoresis (PAGE) analysis of the post-perfusion isolated protein A. Addition of purified protein A to canine antiserum resulted in decreased hemolytic activity of the serum which was associated with increased levels of Clq binding IgG.