Analysis of class II antigen expressing cells in cholesteatoma epithelium

Effects of epidermal Langerhans cell's conditioned medium on keratinocytes: a role of Langerhans cells in cholesteatoma

Langerhans cells (LCs) are known to play an important role in the immunosurveillance system. In this study, as in others, numerous LCs were detected in the epithelial layer of acquired cholesteatoma by immunohistochemical staining. This finding suggests that cell-mediated immune responses are initiated by LCs in cholesteatoma; however, documentation concerning the microenvironment of LCs-keratinocytes in cholesteatoma is limited. Therefore, we investigated the effects of LCs on keratinocytes in vitro. To study these effects it was necessary to isolate and purify LCs. Our present study revealed that good enrichment and a high degree of purity (95%) of LCs could be obtained from neonatal rat skin using the immunomagnetic beads (Dynabeads M-450) sorting technique. These isolated LCs have the biologic activity of LCs, and Langerhans cells' conditioned medium (LCCM) stimulates DNA synthesis in thymocytes. The effect of LCCM on keratinocytes was then studied. We found that (1) LCCM stimulated DNA synthesis in keratinocytes was then studied. We found that (1) LCCM stimulated DNA synthesis in keratinocytes, but not protein synthesis, and (2) LCCM stimulated the incorporation of 3H-putrescine into keratinocytes by the activation of transglutaminase. Transglutaminase is a known marker of terminal differentiation in keratinocytes. By Western blot analysis, we identified a 17-kd immunoreactive mouse interleukin-1 alpha in LCCM. Our results imply that LCs found in cholesteatoma tissue may play an important role in stimulating both hyper-proliferation and cornification of keratinocytes; two characteristic features of cholesteatoma formation. These stimulatory effects may be due to the release of interleukin-1 or other factors by LCs.

Clinical characteristics of cholesteatoma

Clinical characteristics of 99 consecutive patients with acquired and perioperatively established aural cholesteatoma were compared with those of 81 patients with chronic otitis without cholesteatoma (controls). The patients answered a questionnaire, and preoperative and perioperative clinical observations were recorded. There were no presenting symptoms or clinical signs that significantly distinguished the cholesteatoma patients. However, these patients had a significantly higher incidence (45%) of previous middle ear surgery than the control patients (30%). The cholesteatomas were not evident until the time of surgical exploration in as many as 38% of cases. Therefore, surgical exploration appears to be the safest way to identify middle ear cholesteatoma.

Immunohistologic analysis of the cholesteatoma matrix in children

The immunohistological characteristics of retraction pockets, cholesteatoma matrix and granulomatous tissue were compared in 14 samples from pediatric cholesteatoma. The junction between epidermis and the middle ear mucosa appeared as the most inflammatory area, displaying the characteristics of delayed type hypersensitivity. CD1 + Langerhans cells were observed in all epidermic areas, but expressed class II molecules only in the vicinity of polymorphonuclear infiltrates. Numerous mast cells and IgA producing cells were also observed, suggesting that defenses from the mucosal immune system are summoned and contribute to the pathogenesis of cholesteatoma.

The pathogenesis and treatment of cholesteatoma

Congenital cholesteatoma, which arises from embryonic epidermoid tissue, is rare. In the majority of cases the cholesteatoma is acquired. It may develop as a retraction pocket involving the whole membrane, as a result of migration over the perforation edges or as basal cell invasion behind an intact membrane. There is no evidence for a metaplastic process or a Langerhans' cell mediated origin. Treatment modalities include several methods of either conservative or radical surgery, the main aim being one-stage total eradication of cholesteatoma and simultaneous reconstruction. With appropriate surgical methods recurrence figures after 5 years should remain under 10%. The patient's own tissues are the material of choice in the reconstruction.

A comparative study of enzyme histochemical features in the gerbilline and human cholesteatoma

Spontaneous and experimentally induced cholesteatoma in the Mongolian gerbil has been found to exhibit histopathological similarities to human aural cholesteatoma and has been suggested as an experimental model for studies of the clinical situation. In an attempt to further characterize this model, we compared experimentally induced cholesteatomas in the external auditory canal from gerbils with those of the human ear by means of a correlated histopathologic and enzyme histochemical study. The human and gerbilline cholesteatomas revealed similar histopathologic features. Even enzyme histochemically, the human and experimentally induced cholesteatomas demonstrated similar features. Thus glucose-6-phosphate dehydrogenase activity, an indicator of oxidative metabolism, was demonstrated especially in the stratum granulosum cells of the heavily orthokeratinizing squamous epithelium adjacent to the cholesteatomas. The human ear canal skin also revealed enzyme histochemical characteristics similar to the squamous epithelium lining the human cholesteatoma. The hydrolytic enzyme activity (leucyl-aminopeptidase) was strong in the connective tissue surrounding human cholesteatoma when compared with that of ear canal skin. In the gerbilline cholesteatoma, this activity was demonstrated especially in the connective tissue adjacent to eroded bone, which possibly may facilitate cholesteatoma progression. We conclude that experimentally induced cholesteatoma has both histophatological and enzyme histochemical similarities to human aural cholesteatoma and therefore it is suggested that the gerbilline model may be used for studies on the development of human cholesteatoma. Our results support the view that cholesteatoma may originate from migrated hyperkeratinizing cells from the epidermis of the tympanic membrane or the meatus.