UVB-irradiated dendritic cells fail to tolerize murine CD8 naïve or effector T cells.

UVB radiation has been shown to induce T cell tolerance most likely via modulation of the function of antigen-presenting cells like dendritic cells (DC), which are therefore of interest for vaccination therapy. Since little is known about the effects of UVB-irradiated dendritic cells (UVB-DC) on CD8(+) T cells, which are the dominant effectors in various allergic and autoimmune diseases, we have investigated the potential of low dose UVB (100-200 J per m(2)) irradiated bone marrow-derived dendritic cells to induce tolerance in murine CD8(+) T cells specific for the contact allergen trinitrophenyl (TNP) or for a viral peptide. In contrast to the previously reported successful tolerization of primed CD4(+) Th1 cells, neither naïve CD8(+) T cells nor CD8(+) Tc1 effector cells or established CD8(+) T cell clones could be tolerized by TNP-modified or peptide-pulsed UVB-DC in vitro or in vivo. We observed, however, a reduced capacity of UVB-DC to prime naïve CD8(+) T cells. Our data demonstrate an important difference in the susceptibility of CD4(+) and CD8(+) T cells for tolerance induction using low-dose UVB-irradiated DC and have implications for DC therapy of CD8(+) T cell-mediated diseases.