Activation and proliferation of T cells after cocultivation with FV-infected DCs. (A) Naive TCR transgenic CD4⁺ T cells from DO11.10 mice were incubated with infected or uninfected DCs in a 3D collagen gel. After 24 hours, gels were digested and T cells were analyzed for activation marker CD62L, CD69, CD25, CD54, or CD44 surface expression by flow cytometry. T cells were mixed with uninfected (□) or FV-infected DCs (■), which were loaded (+Ova) or not (−Ova) with OVA peptide. T cells without DCs served as negative control (▩). The MFI or the percentage of positive stained cells is shown. Cumulative data from 5 independent experiments are being presented. The error bars represent standard errors of the means. (B) FV-infected (■) and uninfected (●) DCs were loaded with 0.1μg/mL OVA peptide and titrated onto naive TCR transgenic CD4⁺ T cells from DO11.10 mice in a 3D collagen gel. Cells were incubated for 3 days and then pulsed with [³H] thymidine overnight to determine T-cell proliferation. All assays were performed in triplicate. Cultures with DCs that were not loaded with peptide served as negative controls (open symbols). *Statistically significant differences (P < .001) between cultures with FV-infected versus uninfected DCs loaded with OVA antigen. Representative results from 4 independent experiments are shown.