Immunohistochemical detection of interferon-γ-producing cells in dermatophytosis

Skin lesions of dermatophytosis are thought to be a result of a T cell-dependent inflammatory response that is mediated by various cytokines. We examined whether IFN-γ-positive cells (as expression of Th1 response) were present in the skin lesions of dermatophytosis in situ by immunohistochemical techniques. Mixtures of CD4-positive T cells and CD8-positive T cells were found to be present in the dermal infiltrates of the lesions. Considerable numbers of CD1a-positive cells were detected in the upper dermis and epidermis. A marked accumulation of CD68-positive cells was found in the upper dermis. IFN-γ-positive cells were present in the upper dermis of the lesions. The pattern of IFN-γ staining appeared to be intracellular in mononuclear lymphoid cells. The staining was considered to be highly specific because it could be completely blocked by preabsorption with recombinant IFN-γ. Our data support the hypothesis that the skin lesions of dermatophytosis may be associated with a Th1 response. Th1 response, which is characterized by IFN-γ release, is thought to be involved in the host defense against dermatophytes and to reflect cutaneous reaction in dermatophytosis.