Ad5 vectors capsid-displaying retro-DAF complement inhibitor significantly reduce Ad-triggered activation of dendritic cells as well as CD8⁺CD3⁺ and CD8⁻CD3⁺ T cells. Early activation of dendritic cells and T cells was studied by flow cytometric–based methods: 0.75 × 10¹¹ vp/mouse of Ad5-GFP or Ad5-GFP-IX-dDAF_REO were injected intravenously into C57BL/6 mice. Splenocytes were harvested and processed at 6 or 48 hours after injection as described in “Cell staining and flow cytometry”; n = 3 for Mock-injected animals, n = 4 for virus-injected mice. (A) For dendritic cell activation, splenocytes were harvested at 6 hours after injection and stained with the following antibodies: CD11c–phycoerythrin-cyanine 7 (PECy7), CD86–allophycocyanin (APC), CD80-PE. The bars represent mean ± SD. Statistical analysis was completed using 1-way analysis of variance with a Student-Newman-Keuls post hoc test, P < .05 was deemed a statistically significant difference. Values statistically different from those in WT_Mock-injected animals, **P < .001; statistically different values from WT_Ad5-GFP mice, #P < .01, ##P < .001. For CD8⁺CD3⁺ (B) and CD8⁻CD3⁺ (C) T cell activation, splenocytes were harvested at 48 hours after injection and stained with the following antibodies: CD69-PE, CD3-APCCy7, CD19–peridinin chlorophyll protein-cyanine 5.5 (PerCpCy5.5), NK1.1-PECy7, CD8a–Alexa Fluor 700. The bars represent mean ± SD. Statistical analysis was completed with the use of 1-way analysis of variance with a Student-Newman-Keuls post hoc test; P < .05 was deemed a statistically significant difference. Values statistically different from those in WT_Mock-injected animals, *P < .05, **P < .001; statistically different values from WT_Ad5-GFP mice, #P < .05.