Experimental study of resistance to infection by Trichophyton mentagrophytes: demonstration of memory skin cells.

The mechanisms governing the development of local immunity in experimental dermatophytosis were studied by injecting intravenously trichophytin in guinea pigs cured of a prior Trichophyton mentagrophytes infestation. Dermal cell modifications were observed which were greater in the healed zones than in those not affected during the prior dermatophyte inoculation. These modifications included lymphocyte activation and accumulation and an accumulation of basophilic leukocytes. These observations suggest that after an acute dermatophyte infection heals, immunocompetent cells remain which are more numerous at the sites of lesions and that these cells would be responsible for the increased rate of elimination of the fungus during a reinfection. This hypothesis is discussed in the framework of the relationships observed in dermatophyte infections between delayed type hypersensitivity and resistance.