Experimental immune complex otitis media: localization of IgG by protein A-gold technique

Eustachian tube goblet cell density during and after acute otitis media caused by Streptococcus pneumoniae: a morphometric analysis

BACKGROUND

Prior investigations have shown that the number of mucus-producing goblet cells in the middle ear mucosa is highly increased during and up to at least 6 months after experimental acute otitis media. This may, in conjunction with deteriorated eustachian tube function, predispose to subsequent development of secretory otitis media. One reason for the deteriorated tubal function after acute otitis media has been suggested to be an excessive accumulation of mucus secretions, blocking the tube and thereby clearance of the middle ear. This investigation determines the density of the mucus-producing goblet cells in the eustachian tube during and up to 6 months after experimental acute otitis media.

METHODS

Middle ear inoculation of Streptococcus pneumoniae in 25 rats. Groups of five animals, killed on Days 4, 8, 16, 90, and 180. Dissection and decalcification of the eustachian tube, followed by paraffin embedding and serial transverse sectioning, periodic acid-Schiff/Alcian blue staining and morphometric determination of the goblet cell density in every 20th section, using a light microscope.

RESULTS

The goblet cell density was increased on Day 8 and later in the tympanic orificium, in addition to the tympanic and midportion third of the tube. Increased goblet cell density was seen in the pharyngeal third on Days 8 and 16, whereas no changes were registered in the pharyngeal orificium. Pathologic intraepithelial glands formed after the infection and goblet cells were found in mucosal areas normally devoid of these.

CONCLUSIONS

The eustachian tube goblet cell density is increased during and up to 6 months after acute otitis media. Indicated excessive secretion of mucus by more goblet cells may contribute to the deteriorated eustachian tube function found after acute otitis media and thus predispose, sustain, or aggravate middle ear disease.

Immune-mediated otitis media with effusion

This study was designed to clarify the role of immune reaction in otitis media with effusion (OME). Immune-mediated OME was induced in chinchillas, and characteristics of the disease were evaluated biochemically, cytologically, and histologically. OME was induced by a single intratympanic inoculation of keyhole limpet hemocyanin (KLH) in animals which had a high serum anti-KLH IgG titer. In addition, OME was maintained for 3 weeks in seven of 17 chinchillas, boosted by intradermal and intratympanic injections at 1-week intervals. Cells in the middle ear effusion (MEE) consisted substantially of neutrophils, a few macrophages, and other cells. The mean histamine and prostaglandin E2 levels in the MEE significantly exceeded the levels in corresponding sera. The lining membrane of the bullae was edematous and thickened due to dilatation and rupture of blood capillaries and cell infiltration. Next, the animals were inoculated with immune complex into the tympanic cavity. MEE appeared in all treated ears within three days after injection. Biochemical, cytologic, and histologic findings of the immune complex-induced OME resembled those of immune-mediated OME. An immune peroxidase method demonstrated that neutrophils in MEE phagocytose immune complexes. Our findings suggest that a perpetual cycle of inflammatory substances may maintain an inflammatory condition in the middle ear.