EXPERIMENTAL OTITIS-MEDIA WITH EFFUSION INDUCED BY PLATELET-ACTIVATING-FACTOR

This study tested the hypothesis that platelet activating factor (PAF) in the middle ear can induce otitis media with effusion (OME) and tha t PAF antagonists can prevent PAF-induced OME. An initial trial of 16 mug of PAF was injected into chinchilla bullae, and all ears developed middle ear effusion (MEE) within 48 hours. Subsequent trials were per formed to test dose dependency. Interestingly, 1 or 16 mug of PAF caus ed more MEE and inflammation than did 4 or 8 mug. A dose of 0.5 mug PA F did not cause MEE. Middle ear effusion from injected bullae containe d the full spectrum of lipoxygenase and cyclooxygenase products; addit ionally, more PAF was detected than was injected. Finally, a PAF antag onist (WEB 2170) injected intraperitoneally prevented PAF-induced OME. This study demonstrates that PAF injected into the middle ear can ind uce OME and that PAF antagonists effectively prevent PAF-induced OME. These findings suggest that PAF plays an important role in the pathoge nesis of OME.