The role of immune complex in otitis media with effusion

Fifteen chinchillas were inoculated with immune complexes of Streptococcus pneumoniae into the tympanic cavity, and with formalin-killed bacteria into the opposite side. Middle ear effusion (MEE) were found in 14 ears having inoculation with immune complexes and in only four ears having inoculation with formalin-killed S. pneumoniae. In another experiment, 20 chinchillas received intra-tympanic inoculation with live S. pneumoniae after systemic immunization with formalin-killed S. pneumoniae of the same strain. As a control, 12 chinchillas were inoculated with live bacteria of the same strain into the tympanic cavity without pre-immunization. MEE was observed in nine of pre-immunized animals and persistent MEE lasting for more than 3 weeks was observed in seven of the animals. In control, persistent MEE was not observed, though six animals developed otitis media with effusion (OME). The results suggest that the formation of immune complexes in the tympanic cavity plays an important role in the occurrence of persistent MEE after peumococcal otitis media.