Effect of preopsonization on phagocytosis of Haemophilus influenzae

Because bacteria are known to persist in middle ear effusions for extended periods of time despite the presence of increasing titers of specific antibody in both sera and middle ear fluids in humans, we examined the ability of postinfection serum to opsonize Haemophilus influenzae (nontypable and type b) for phagocytosis by middle ear macrophages in chinchillas. Our data indicated that preopsonization of both strains of H influenzae enhanced phagocytosis by macrophages recruited to the middle ear following intrabullar instillation of keyhole limpet hemocyanin. Both the total number of bacteria ingested and the percentage of macrophages phagocytizing were significantly greater in the presence of postinfection serum than preinfection serum for all animals tested.