[Ultrastructural study of host-parasite relationships in epidermis during "Trichophyton mentagrophytes" infection (author's transl)].

This study presents information concerning (1) location of fungal cells within the tissue, (2) subsequent tissue alterations and (3) behaviour of immunocompetent cells. 1) During initiation of infection, the fungal cells were found to be intracellular in the lower parts of stratum corneum. Digestion of intracellular keratin is obvious, but the resistant cell wall of the squames remain unaltered. During reinfection fungal cells were located intercellulary in the upper parts of stratum corneum. 2) The study of ultrastructural changes in the underlying viable parts of epidermis reveals many alterations of keratinocytes such as mitochondrial damage, lost of tonofilaments, vacuolization, and rupture of cytoplasmic bonds. The epidermal cells are disjoined by an oedematous reaction, and these manifestations may involve large epidermic areas. 3) Cells, arising from the dermis, move into the intercellular spaces that originate from epidermal cellular dissociation. These cells are interpretated as corresponding mainly to lymphocytes, monocytes and macrophages. This cellular infiltration is intense. Most of the lymphocytes and macrophages are activated (even giant cells are to be observed). In addition, some of these cells may reach the stratum corneum, the area of parasitic location. The relationships between these manifestations and those related to cutaneous delayed hypersensitivity reactions are discussed. It seems possible to demonstrate the immunopathologic status of the reaction where some specific immunological manifestations appear to be related to the fungal growth acting in a special way by antigenic stimulation.