IGG SUBCLASS RESPONSE AND OPSONIZATION OF STREPTOCOCCUS-PNEUMONIAE AFTER VACCINATION OF HEALTHY-ADULTS

Studies relating opsonization and IgG antibodies to Streptococcus pneumoniae have yielded contradictory results. This study compared changes in opsonization with IgG subclass response after vaccinating healthy subjects with a 23-valent pneumococcal vaccine. Total IgG and IgG subclass antibodies to pneumococcal polysaccharide types 8, 9, and 19 were measured by ELISA. Opsonic activity was assayed using 3H-Iabeled bacteria and polymorphonuclear leukocytes in different serum concentrations (5%–40%). A substantial postvaccination increase in total and subclass IgG antibody was observed in most subjects, although variations were seen. Postvaccination sera generally gave rise to enhanced opsonization, and a correlation was found between increases in antibody levels and opsonization. This correlation was closest for IgGl and IgG4 and generally strongest at the lowest serum concentration, but weak 01: absent at the highest concentration. Thus, vaccination against S. pneumoniae stimulates a variable increase in specific opsonic activity in healthy persons that is best demonstrated when serum is a limiting factor in the opsonin assay. © 1990, by The University of Chicago.