ELISA detection of human IgG subclass antibodies to Streptococcus mutans

A sensitive enzyme-linked immunosorbent assay (ELISA) has been developed to measure IgG subclass antibodies against whole cells of Streptococcus mutans and to a purified streptococcal antigen (SA I/II). Bacterial cells were bound to the solid phase using methyl glyoxal and mouse monoclonal antisera against IgG and each IgG subclass were used to detect antibodies. Natural antibodies to S. mutans were predominantly of the IgG1 and IgG2 subclasses, though IgG3 and IgG4 antibodies were detectable in most subjects, and were the majority response in a few subjects. Antibodies to SA I/II were predominantly of the IgG1 subclass with virtually no activity detectable in the IgG3 and IgG4 subclasses. Inhibition studies suggested some restriction of IgG subclass responses to bacterial antigens since SA I/II and c polysaccharide could inhibit binding of all subclasses to whole cells of S. mutans equally, whereas glucosyltransferase, lipoteichoic acid and dextran showed greatest inhibition of the IgG3 and IgG4 subclasses.