title: Passive protection by human serum in mice infected with encapsulated Staphylococcus aureus.
abstract: The occurrence and nature of passive protective antibody in 100 samples of human serum was investigated in mice challenged with strains of Staphylococcus aureus capsular types A (Smith diffuse strain) and B (strain NS58D). Sixty of the sera passively protected mice against the capsular type-A strain, three against type B, and one against both types. Rabbit antisera against human IgG, IgA and IgM could remove the protective activity from a human serum of high potency, and the activity was also sensitive to 2-mercaptoethanol. Absorption with Smith surface antigen removed protective activity and reduced the concentration of IgG 7-fold, IgA 2.7 fold and of IgM 3-fold more than in a non-protective serum. Consequently, the protective activity of human serum is believed to be associated with antibodies to the S. aureus capsular antigen in the three immunoglobulin classes.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D002473:Cell Wall / Q000276:immunology; D006801:Humans; D007112:Immunity, Maternally-Acquired; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D007136:Immunoglobulins / Q000276:immunology*; D051379:Mice; D013203:Staphylococcal Infections / Q000276:immunology*; D013211:Staphylococcus aureus / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins