Fig. 4.

HPV16-exposed LC treated with Poly-ICR induce T cell proliferation and an HPV16-specific CD8+ T cell response. (A) Mixed lymphocyte reaction. Proliferation of allogeneic T cells by HPV16-exposed LC treated with Poly-ICR. LC were left untreated or exposed to HPV16 VLP for 6 h (N=4 individual donors). Subsequently, the cells were treated with s-Poly-I:C (5 μg/mL Poly-ICR) for 48 h. LC were co-cultured with purified MHC-mismatched T cells from a healthy donor for 6 days in triplicate wells. ³H-thymidine was added during the last 18 h of culture. Shown is the mean cpm thymidine uptake (± SEM) ^⁎p<0.05 compared to untreated LC (one-way ANOVA, Tukey׳s post-test). (B) In vitro immunization. Purified CD8⁺ T cells were co-cultured with s-Poly-I:C (5 μg/mL Poly-ICR) treated or untreated autologous LC for 4 weeks with weekly restimulations in an in vitro immunization assay. LC were loaded with HPV16 L1L2-E7 cVLP, then treated with s-Poly-I:C or left untreated. T cells were then tested for IFN-γ secretion in response to HLA-A*0201 binding peptides by ELISPOT analysis. The number of spots representing IFNγ secreting cells was averaged over eight replicate wells. Data show two representative HLA-A*0201⁺ donors following s-Poly-I:C treatment of LC out of five donors tested.