The effect of complement depletion on immunologically mediated middle ear effusion and inflammation.

Immunologic injury during immune response to antigen in the middle ear cavity has been suggested to be a contributing factor in otitis media with effusion (OME). One of the mechanisms proposed involves the generation of immune complexes, with subsequent injury mediated by complement fixation. To evaluate the potential role of complement in OME, an animal model of immune-mediated middle ear effusion and inflammation was used. Antigenic challenge of the middle ear of normal, sensitized guinea pigs results in OME. This response was compared with that observed in guinea pigs whose sera were decomplemented by treatment with cobra venom factor. As compared to controls, decomplemented animals exhibited less effusion [130 (+/- 35) vs 83 (+/- 60) microliter, P less than 0.05] and inflammation in the middle ear following antigenic challenge. These results suggest that complement could play a role in the pathogenesis of OME. However, the fact that animals with severely depleted serum complement still displayed a moderate amount of effusion and inflammation indicates that other mechanisms are also involved in our model of immune-mediated OME.