An animal model for cell-mediated immune responses to dermatophytes

Abstract

Guinea pigs infected with three species of dermatophytes were tested for cell-mediated immune responses, including delayed cutaneous hypersensitivity, lymphocyte transformation (LT), macrophage migration inhibition (MMI), and passive transfer of hypersensitivity. The patterns of reinfection disease were also analyzed as an index of altered host immunity. The fungi tested represented the three genera of dermatophytes ( Trichophyton, Microsporum, and Epidermophyton), and included zoophilic and anthropophilic species. Microsporum vanbreuseghemii, the zoophilic species, produced the most virulent infection, and Epidermophyton floccosum, previously considered obligately anthropophilic, produced the mildest infection. The clinical stages of reinfection were condensed for all three species, and all infected animals manifested delayed-type cutaneous hypersensitivity to homologous antigen, which persisted up to 12 months. There was a significant MMI and LT by cells from infected animals exposed to homologous antigen. Cutaneous hypersensitivity was transferred by splenic, lymph node, and peritoneal exudate cells from infected donors. The severity of primary infection correlated with the duration and magnitude of reinfection symptoms, and with the persistence of hypersensitivity. These results indicate that there are systemic CMI responses to these fungi which usually do not invade beyond the keratinized layers of skin, hair, and nails.