Measurement of a staphylococcal antibody in human serum by a mouse protection test

The adhesion of protein A-bearing Staphylococcus aureus organisms to soluble-staphylococcal-antigens-coated HeLa cells mediated by specific antibodies

The adhesion of staphylococcal protein A (SpA)-bearing Staphylococcus aureus Cowan I organisms to HeLa cells was enhanced by pretreatment of HeLa cells with staphylococcal extracellular antigens and antibodies to them. The adhesion of HLj, an SpA-poor mutant derived from Cowan I, to HeLa cells was not enhanced by the same pretreatment of HeLa cells. Furthermore, the enhanced staphylococcal adhesion was inhibited by soluble SpA. The antigen(s) responsible for the enhanced staphylococcal adhesion was(were) heat stable. Pretreatment of HeLa cells with the mixture of staphylococcal extracellular antigens and antibodies to them also enhanced the adhesion of Cowan I. Similarly the adhesion of Cowan I was enhanced by pretreatment of HeLa cells with extracellular antigens of Pseudomonas aeruginosa and antibodies to them. These results indicated that cell-bound SpA mediated the binding of S. aureus to immune complexes composed of extracellular bacterial products and antibodies to them bound to the surface of HeLa cells, and suggested another role of cell-bound SpA as a co-adhesin with other factors in infections due to S. aureus.

Mouse-protective antibodies in human sera against the Smith strain of Staphylococcus aureus

We confirmed the widespread occurrence in human sera of antibodies able to protect mice from the lethal effect of the Smith strain of Staphylococcus aureus injected intraperitoneally together with hog gastric mucin. We were unable to demonstrate that the antibody was active against other naturally occurring strains of S. aureus nor did such strains absorb the protective antibody from serum.Repeated passage of two of the above strains of S. aureus in the peritoneal cavities of mice produced more virulent daughter strains. Human sera containing protective antibodies against the Smith strain also protected mice against these daughter strains, but the daughter strains also were unable to absorb the protective antibody from human sera. This suggests the existence in human sera of more than one kind of antibody protective against staphylococci.

ANTIBODIES AGAINST STAPHYLOCOCCUS AUREUS IN NONIMMUNIZED RABBITS

Cohen, Jay O. (Communicable Disease Center, Atlanta, Ga.), Glenda S. Cowart, and William B. Cherry . Antibodies against Staphylococcus aureus in nonimmunized rabbits. J. Bacteriol. 82: 110–114. 1961.—Antibody against staphylococci was demonstrated in the serum of each of 36 nonimmunized specific-pathogen-free rabbits that were tested. Evidence obtained is in agreement with the proposition that two distinct staphylococcal antibodies are present in the sera from these nonimmunized rabbits. One is responsible for agglutination of Staphylococcus aureus Cowan serotype I, and the other for the formation of a reaction line observed in Ouchterlony plates with soluble antigens of both Cowan serotype I and Cowan serotype III.

Fluorescent antibody reagent prepared from preimmune rabbit serum stained some strains of coagulase positive staphylococci, including Cowan's types I and III, and failed to stain any of 14 coagulase negative strains.

The sera of rabbits obtained from a commercial source were shown to contain other antibodies for staphylococci in addition to the two found in the sera of specific-pathogen-free rabbits. The data suggested that rabbits from commercial sources have had contact with a great variety of antigens capable of stimulating staphylococcal antibody.

Evidence demonstrated that normal rabbit serum from specific-pathogen-free animals of our colony could be used for differentiation of certain staphylococcal strains.