Immunologically activated cells in aural cholesteatoma.

In this immunohistochemical study, we characterized the cells infiltrating the stroma of acquired aural cholesteatomas in detail, using a panel of monoclonal antibodies directed against immune cell type-specific antigens, HLA class II antigens, and interleukin-2 receptor. For all antibodies used, normal ear skin was stained for comparison. The vast majority of the infiltrating cells was CD45-positive, ie, derived from bone marrow. Reactivity with anti-CD3 and anti-CD6 antibodies revealed an abundant infiltration of T lymphocytes beneath the squamous epithelium of cholesteatoma. The B lymphocyte-specific anti-CD19 and anti-CD22 antibodies detected only occasional positive cells. Hence, the cellular infiltrate in the stroma of aural cholesteatoma is made up primarily of T cells with macrophages scattered between them. Expression of HLA-DR was almost as high as that of CD45, whereas CD25-positive cells were detected in lower amounts. We infer that the majority of T cells and macrophages in the stroma of cholesteatoma are in an immunologically activated state. The characteristics of the infiltrating cell population suggest an antigen-driven process in cholesteatoma.