Soluble L-selectin and interleukin-8 in otitis media with effusion

adhesion of leukocytes to vascular endothelium and their invasion into local tissues are important steps in inflammation. L-selectin plays a crucial role in leukocyte rolling and adhesion on endothelial cell surface. Interleukin-8 (IL-8) is a potent chemotactic substance toward neutrophils and lymphocytes-T and mediate their migration to local inflammation. The levels of soluble L-selectin (sL-selectin) and IL-8 were measured in middle ear effusions (MEE) from children with otitis media (OM) to estimate their role in pathogenesis of inflammation in middle ear.

MEE were collected from 113 ears of 62 children during routine myringotomy. The entire specimen was diluted with phosphate-buffered saline (PBS) to 2 ml and centrifugated at 1500 rpm for 15 min to separate cellular components. Supernatants of MEE were stored frozen at -20 degrees C for sL-selectin and at -80 degrees C for IL-8 assessment. The concentration of sL-selectin and IL-8 were estimated with ELISA and compared with total protein concentration measured by Bradford assay.

MEEs from children with chronic mucous otitis media contained significantly higher mean concentrations of IL-8 559.4 pg/mg total protein (TP) (+/-535.6) in comparison with normal serum 17.79 pg/mg TP (+/-10.9), serous OM 40.3 pg/mg TP (+/-28.1) and purulent OM 104.4 pg/mg TP (+/-128.6). High concentration of IL-8 was found in MEE from the children with early recurrence of OMS. The levels of sL-selectin were higher in purulent effusions 77.2 ng/mg TP (+/-67.4) than those of chronic mucoid 27.6 ng/mg TP (+/-36.7) and serous OM 26.3 ng/mg TP (+/-27.1).

the results support a hypothesis that IL-8 can be responsible for prolongation of inflammatory process in middle ear, therefore long-term treatment and observation of children with the high levels of IL-8 in MEE may be necessary. Elevated level of sL-selectin in acute OM suggests the involvement of L-selectin in the acute phase of OM.