Significance of kallikrein-kinin system in otitis media with effusion.

Significance of the kallikrein-kinin system in the pathogenesis of otitis media with effusion (OME) was evaluated by prekallikrein level, kallikrein activity, and concentration of high molecular weight (HMW) kininogen in 45 middle ear effusions (MEEs, 38 serous and seven mucoid). All MEEs had varying prekallikrein levels (73.1 +/- 127.5 relative fluoro units [RFU]), and the mean value in serous effusions (82.2 RFU) was much higher than that in mucoid effusions (23.0 RFU). Hydrolytic activity of kallikrein in serous effusions was 18.0 +/- 27.9 RFU, and was significantly higher than that in mucoid effusions (8.0 +/- 4.2 RFU, p less than 0.05). Concentration of HMW kininogen in serous effusions was 51.2 +/- 72.77% of plasma value, but it could not be detected in any mucoid effusions. Analysis of protein composition by polyacrylamide gel electrophoresis indicates that plasma protein that has leaked into the middle ear is a major component of MEEs. The kallikrein-kinin system would be active in serous effusions, and liberated bradykinin enhances vascular permeability in the middle ear mucosa, leading to profuse plasma leakage, which characterizes the component of serous effusions. On the other hand, this system would almost be consumed in mucoid effusions.