Acute tympanic membrane perforations and the early immunological response in rats

Abstract

Conclusions: This study showed that macrophages, B cells, and T cells occurred at different frequencies, localizations, and times after acute laser tympanic membrane perforation. Immunological cells were most prevalent in the proliferative mass adjacent to the annulus region. The cellular immunological response in freshly perforated eardrums was unexpectedly aggressive. Objectives: To study the occurrence of immunocompetent cells during the healing process of fresh perforated tympanic membranes. The information could be used to develop alternative outpatient procedures in the cure of chronic perforations, replacing conventional surgery. Materials and methods: A laser myringotomy was carried out in Sprague-Dawley rats, which were sacrificed at 3 and 6 days after the myringotomy. Tympanic membrane sections were stained immunohistochemically according to the avidin-biotin method, targeting macrophages, B cells, and T cells. Semi-quantification was performed; positive cells were counted and mean values were calculated. Results: Macrophages and B cells were most frequent at day 6 and T cells at day 3 after laser myringotomy. B cells were the most prevalent studied cell type. T cells peaked at day 3, after which they decreased in number. Most immunocompetent cells were observed in the proliferative mass at the edge of the perforation.