Prekallikrein-Kallikrein System in Middle Ear Effusion

Abstract

The level of prekallikrein and hydrolytic activity of trypsin, glandular kallikrein and lysosomal cathepsin B in middle ear effusions (MEEs) were measured by the fluorometric assay. MEEs (25 serous and 5 mucoid) had variable prekallikrein level of which mean value was 53.4±103.0 relative fluoro unit (RFU); 61.6 in serous and 12.3 in mucoid effusions. Hydrolytic activity of cathepsin B was much higher than that in plasma, and was 34.9±42.9 RFU; 35.1 in serous and 33.8 in mucoid effusions. Serous effusions could be divided into two groups; one (n=9) with high prekallikrein level (over 50 RFU) and the other (n=16) with low level (under 10 RFU), and their protein bands examined by polyacrylamide gel electrophoresis were very similar to those in Plasma. Hydrolytic activity of glandular kallikrein and trypsin was low in all the MEEs. These results suggest that the level of prekallikrein in MEEs is the significant parameter to reflect the degree of plasma leakage into middle ear, which is very low in mucoid effusions and very varied in serous effusions at the time of sampling. It is concluded that plasma leakage into middle ear and damage of secretory function in middle ear mucosa are two important factors related to the production of MEE.