Uptake and degradation of staphylococcal protein A-IgG and HSA-IgG complexes by peritoneal macrophages from rabbits, guinea-pigs and mice.

Normal rabbit serum formed soluble complexes with protein A(pA) which were not taken up or broken down by rabbit peritoneal exudate (PE) cells. On the other hand, normal guinea-pig and mouse sera formed precipitating complexes with pA which were rapidly degraded by the appropriate PE cells. Rabbit, guinea-pig and mouse antisera towards staphylococcal pA formed precipitating complexes with pA, all of which were rapidly ingested and degraded by the homologous PE cells. Soluble and precipitated IgG complexes were identified by zone electrophoresis in agar with subsequent autoradiography. Precipitating complexes were formed when 125I-HSA was added to homologous rabbit, guinea-pig and mouse antisera, and these complexes were rapidly ingested and degraded by the corresponding PE cells. Thus, staphylococcal pA-IgG complexes (Fc-bound material) are ingested and degraded to the same extent as similar antigen-antibody complexes (Fab-bound material).