Enhanced contact hypersensitivity by delayed T-helper 2 response in BALB/c mice

T-helper (Th) 1/Th2 balance determines the direction of contact hypersensitivity (CHS). To clarify the immunopathogenesis of contact dermatitis, 2,4-dinitrofluorobenzene (DNFB)‐induced CHS reaction was compared between the BALB/c and C57BL/6 mice. The two strains were sensitized with DNFB systemically and challenged with DNFB locally. The CHS reaction in BALB/c mice was intense compared with that in C57BL/6 mice at 24 and 48 hours post-DNFB challenge. The dermal lesions were characterized by infiltration of lymphocytes, eosinophils, neutrophils, and macrophages including CD4⁺ and CD8⁺ T cells, and interleukin (IL)-4‐producing⁽⁺⁾ and interferon (IFN)-gamma⁺ cells in BALB/c mice. In C57BL/6 mice, the composition of inflammatory cells was same as those in BALB/c mice except for eosinophils, CD4⁺ T cells, and IL-4⁺ cells. There was no increase in the number of mast cells in the two strains. Local and systemic productions of IL-4 and IFN-gamma in BALB/c mice were higher than those in C57BL/6 mice. Although blood IgE values increased in BALB/c mice, but not in C57BL/6 mice, at 48 hours postchallenge, its value was low. The delayed Th2-like response together with Th1-like response in BALB/c mice may induce strong CHS reaction compared with C57BL/6 mice, which may dominantly develop Th1-like reaction. Moreover, mast cell and IgE do not appear to be involved in delayed CHS.