IgG subclass distribution of antibodies after vaccination of adults with pneumococcal conjugate vaccines.

The serum IgG subclass response of adults to Streptococcus pneumoniae (Pnc) capsular polysaccharides (PS) 6B, 14 and 23F was measured for four Pnc vaccines: the 23-valent PS vaccine or PS-protein conjugates with diphtheria toxoid (PncD), tetanus protein (PncT) or CRM197 protein (PncCRM) carriers. A standardized enzyme-linked immunosorbent assay specific for IgG subclasses was employed. This assay uses pneumococcal reference serum, lot 89-SF, to which anti-Pnc PS IgG subclass concentrations have been assigned. Both IgG1 and IgG2 responses were more frequent and higher in the conjugate groups than in the PS group. IgG subclasses in subjects vaccinated with PS displayed similar IgG2 predominant distribution previously observed in both natural and vaccine-induced antibodies. Antibodies induced by PncT, however, had a significantly altered IgG2/IgG1 ratio (P < 0.05), with a higher proportion of IgG1.