Immunohistochemical localization of activated and mature CD83⁺ dendritic cells in granulomas of sporotrichosis

Dendritic cells (DC) are considered to be the most potent antigen-presenting cells (APC) and CD83 is expressed at a high level on immune-competent, activated and mature DC. In order to obtain insight into the immune response in sporotrichosis, we searched immunohistochemically for CD83⁺ DC in the granulomatous skin lesions of patients. A small but significant subpopulation of CD83⁺ DC (approximately 0.2 to 0.8% of inflammatory cells) was found. The most common distribution pattern of CD83⁺ DC was as clusters with mononuclear lymphoid cells within the granulomas. In addition, CD83⁺ DC were occasionally scattered around the granulomas. High-intensity staining of CD83 antigens was detected not only on the surface, but also in the cytoplasm of DC. No CD83⁺ DC were observed in the epidermis. A considerable amount of CD1a⁺ cells were detected in the epidermis, papillary dermis and around the granulomas, but CD1a⁺ cells were rarely found within the granulomas. There were large numbers of CD68⁺ monocytes and macrophages in the granulomas. These results indicate that activated and mature DC may play a role in the immune response to sporotrichosis.