Immunochemical Characterization of Staphylococcal and Micrococcal Mucopeptides

Mucopeptides from one Staphylococcus aureus, two Staph. epidermidis and two Micrococcus strains have been prepared and examined for chemical composition and for serological activity. The chemical analyses showed differences in the mucopeptide structures, especially between staphylococci and micrococci, some differences appearing to be related to variations in the inter‐peptide bridges. No precipitation was observed, but agglutination was obtained in antisera to whole bacteria as well as in antisera to mucopeptides. Cross‐absorption studies showed the presence of shared and specific antigenic determinants. None of the mucopeptides sensitized erythrocytes for agglutination in antisera, but the staphylococcal mucopeptides, in contrast to the micrococcal, induced the production of haemagglutinins in rabbits. Antibodies to mucopeptides were found in human serum and colostrum. The sera contained antibodies of the IgG class; colostrum mostly IgA antibodies. Sera with increased anti‐staphyiolysin titres contained higher amounts of IgG than normal sera. Fab but not Fc fragments of IgG were found to bind to mucopeptide, and complexes of mucopeptide and IgG fixed complement. Injection of mucopeptides into rabbit and human skin provoked dermonestronic reactions.