Immunoglobulin G class and subclass antibodies to pneumococcal capsular polysaccharides

Enzyme immunoassays were developed to measure immunoglobulin G (IgG) and IgG1-4 subclass antibodies to pneumococcal capsular polysaccharides (PCP) types 4 and 7F. In healthy subjects, anti-PCP antibodies were predominately of the IgG1 and IgG2 subclasses. There was a significant increase in IgG, IgG1, and IgG2 anti-PCP antibody concentrations following immunization with pneumococcal vaccine. IgG and IgG2, but not IgG1, anti-PCP antibody concentrations correlated with total anti-PCP antibody concentrations measured by the standard radioimmunoassay and with serum opsonic activity for serotype 7F Streptococcus pneumoniae. Such IgG and IgG subclass antigen-specific antibody assays may be useful to investigate the immune response to pneumococcal polysaccharides.