Immunological aspects of urethral stenosis. Involvement of the S100 protein-positive dendritic cells

— Within the superficial layers of healthy skin and of some mucosae there is a Population of accessory cells of the immune system, able to interact with T helper lymphocytes. Such cells, called tissular dendritic cells (DCs), increase their density and display different morphological features in a variety of immunologically-mediated dermatological disorders. In the present work we investigated DCs within the various urethral segments, both in normal conditions and in urethral stenosis. The specimens, obtained from urethrectomies and urethroplasties with end-to-end anastomosis, were stained with anti-S100 protein antibody and immunofluorescence techniques. We demonstrated an increasing density of S100 protein-positive epithelial DCs from the Prostatic urethra to the glandular one, where DCs were also larger and richer in dendritic Processes. In urethral stenosis the intraepithelial infiltrate of ramified DCs was much denser than any other control. We therefore hypothesize a role for the immune system in the development and maintenance of urethral stenoses, where, as already demonstrated for other types of pathological scarring, morphological changes of DCs serve as clues to their functional activation.