DENDRITIC EPIDERMAL T-CELL INVOLVEMENT IN INDUCTION OF CD8(-CELL-MEDIATED-IMMUNITY AGAINST AN ULTRAVIOLET RADIATION-INDUCED SKIN TUMOR() T)

Murine epidermis contains 2 distinct cell populations which contribute to the skin immune system, Langerhans cells (LC), and dendritic epide rmal T cells (DETC). LCs are important in the induction of immunity ag ainst a wide range of antigens; however, the function of DETC is uncle ar. To investigate the roles of these epidermal cells (EC) in protecti ve antitumor immunity, an in vivo model of an ultraviolet radiation-in duced fibrosarcoma, UV-13-I, was used. Mice were immunized with tumor antigen-pulsed EC followed IO days later by an injection into the ear of 10(5) tumor cells, which did not lead to formation of a detectable tumor, but was intended to simulate the influence of a developing tumo r on the ensuing immune response. The mice were then challenged with 2 x 10(6) viable tumor cells in each flank, sufficient to result in gro wth of a measurable tumor, Protective immunity was induced by DETC, an d shown to be long-lasting, with tumors inoculated 160 days after immu nization being effectively rejected, The effector cells responsible fo r protective immunity were CD8(+) T cells. Delayed-type hypersensitivi ty generated by tumor antigen-pulsed EC was dependent on LCs, with no involvement of DETCs, This response, in contrast to that of DETC, requ ired prior culture of EC with GM-CSF, but failed to inhibit tumor grow th or incidence. Thus DETC and LC can both activate antitumor immune r esponses, although only the DETC-dependent response results in protect ive immunity in the presence of a developing tumor. (C) 1997 Wiley-Lis s, Inc.