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Immunotype findings in macrophages in aural cholesteatomas
B Negri1, V Schilling, J Bujia
1Ludwig-Maximilians-Universität, Klinikum Grosshadern, Klinik und Poliklinik für Hals-Nasen-Ohrenkranke, Munich, Federal Republic of Germany.
Insights
Aural cholesteatomas show increased numbers of specific macrophage populations in their stroma. These findings suggest these immune cells may play a role in the pathology of cholesteatoma.
Area of Science:
- Immunology
- Otolaryngology
- Pathology
Background:
- Aural cholesteatomas are characterized by significant cellular infiltration in the stromal tissue.
- Understanding the specific cell types within this infiltrate is crucial for elucidating disease mechanisms.
Purpose of the Study:
- To characterize the immune cell populations, specifically monocytes/macrophages, within the stroma of aural cholesteatomas.
- To compare the distribution and characteristics of these cells to normal ear skin.
Main Methods:
- Utilized monocyte/macrophage-specific monoclonal antibodies (KiM1+, KiM6+) to identify and quantify phagocytic cells.
- Examined six excised cholesteatoma specimens and compared them to control tissues.
- Assessed the localization and density of macrophages within the cholesteatoma stroma and normal ear skin.
Main Results:
- Phagocytic cells (KiM1+, KiM6+) were found in significantly higher numbers (two- to fourfold) in cholesteatoma stroma compared to controls.
- Macrophages in cholesteatomas were evenly distributed, unlike the perivascular localization in normal skin, due to the avascular nature of the cholesteatoma stroma.
- No Mac 387+ macrophages were detected in cholesteatomas, contrasting with their presence in diseased skin.
Conclusions:
- The study identified a substantial population of macrophage-like phagocytic cells within aural cholesteatomas.
- The distribution and characteristics of these cells suggest an active role, potentially in an autoimmune process, contributing to cholesteatoma pathogenesis.
Abstract:
Since a heavy cellular infiltrate is seen in the stroma of most aural cholesteatomas, we attempted to characterize this cell population in more detail using monocyte/macrophage-specific monoclonal antibodies. KiM1 + (specific for CD11c antigen, the 150 kDa alpha-chain of a leukocyte integrin), and KiM6+ phagocytes were present in two- or fourfold higher numbers in the stroma of the six excised cholesteatomas than in the control tissues. Since the stroma of the cholesteatoma is devoid of microvessels, the typical perivascular localization of dermal macrophages was not seen in the cholesteatomas studied. The density of the macrophages in the normal ear skin was much higher in the upper dermis than in the lower dermis. In the cholesteatomatous specimens, the phagocytes were evenly scattered within the connective tissue and the cellular infiltrate. In contrast to diseased skin, no Mac 387+ macrophages were detected in the cholesteatomas. A great number of phagocytic cells closely resembling dermal macrophages was found in the stroma of the cholesteatomas and probably contributes to an active autoimmune process.