The immune response to Trichophyton tonsurans: distinct T cell cytokine profiles to a single protein among subjects with immediate and delayed hypersensitivity.

Skin testing with an extract from the dermatophyte fungus Trichophyton tonsurans can result in either immediate (IH) or delayed hypersensitivity (DH). These experiments were designed to examine in vitro T cell cytokine production in response to purified proteins from T. tonsurans in subjects with different skin test reactivities. Peripheral blood mononuclear cells were obtained from subjects with immediate, delayed, or negative skin tests, and cellular proliferation was studied. Subjects with either IH or DH had positive proliferative responses to crude extracts and two purified proteins, protein IV (83 kDa) and Tri t 1 (30 kDa). Nine cell lines were established from 5 IH subjects, which produced a cytokine profile characteristic of Th2/Th0 cells, i.e., ratio of IFN-gamma to IL-4 or IL-5 <2:1. By contrast 8 of 10 cell lines from DH subjects had a Th1 profile, i.e., IFN-gamma to IL-4 or IL-5 >20:1. Lymphocytes from subjects with negative skin tests show very poor proliferative responses; however, 6 cell lines derived from these individuals showed a cytokine profile characteristic of Th1 cells. Levels of IL-5 were significantly different when comparing the IH group with the DH group (p < 0.001). The results demonstrate that a single defined protein from T. tonsurans can produce distinct T cell cytokine profiles that correspond to in vivo skin test reactivities and serum Ab levels.