CD8TC1 AND TC2 CELLS SECRETE DISTINCT CYTOKINE PATTERNS IN-VITRO AND IN-VIVO BUT INDUCE SIMILAR INFLAMMATORY REACTIONS

Naive CD8 T cells, similar to CD4 T cells, can differentiate into at l east two subsets of cytolytic effector cells with distinct cytokine pa tterns: T cytotoxic-1 (Tc1) cells secrete a Th1-like cytokine pattern, including IL-2 and IFN-gamma; and Tc2 cells produce Th2 cytokines, in cluding IL-4, IL-5, and IL-10. As CD4 Th1 cells induce delayed-type hy persensitivity (DTH) more effectively than Th2 cells, we tested the po tential ability of Tc1 and Tc2 cells to induce DTH. Allospecific Tc1 o r Tc2 cells were injected into the footpads of naive mice expressing t he target Ag. Tc1 and Tc2 cells induced comparable levels of Ag-specif ic footpad swelling with similar kinetics. They also induced similar l evels of footpad edema and similar infiltration of macrophages and neu trophils. However, Tc2 cells induced slightly more eosinophil infiltra tion. Analysis of footpad extracts showed that Tc1 and Tc2 cells retai ned their distinct in vitro cytokine profiles in the injected footpads . These results suggest that both Tc1 and Tc2 cytokines can be associa ted with the DTH reaction induced by CD8 T cells. Perforin-deficient T c1 or Tc2 cells also induced DTH, although at lower levels, suggesting that perforin-mediated cytotoxicity of CD8 T cells is not essential f or CD8-induced DTH. Thus, despite their distinct cytokine profiles in vitro and in vivo, Tc1 and Tc2 cells induce similar DTH reactions.