Serous Otitis Media:Immunoglobulin and Lysozyme Levels in Middle Ear Fluids and Serum

The middle ear fluids of seven patients with bilateral, and five patients with unilateral serous otitis media (SOM), were demonstrated to be microbiologically sterile when assessed for the presence of bacteria, mycoplasma, viruses, and fungi. The concentrations of immunoglobulins G, M, A, D, and lysozyme (muramidase) were determined in the serum and middle ear fluids. Lysozyme levels of middle ear aspirates were found to be elevated in SOM patients. The elevated levels of lysozyme in combination with the antibody-containing classes of immunoglobulins may explain the microbiologically sterile condition of the middle ear fluids of SOM patients. Also, the elevated lysozyme concentrations in middle ear fluids may indicate the previous presence of neutrophils and hence a previous inflammatory insult. The increased levels of IgA demonstrated in middle ear fluids may indicate local synthesis of secretory IgA by secretory cells of Eustachian tube and middle ear. The closed Eustachian tube, partial vacuum conditions and absence of a portal of exit for accumulated serous fluids are offered as a possible explanation for SOM.