FGK4.5 treatment during VSV vaccination enhances the functional avidity and poly-functionality of secondary effector CD8⁺ T cells.

<p>C57BL/6 mice were i.v. infected with 2×10³ cfu LM-ova, or with 2×10⁵ pfu VSV-ova, or 2×10⁵ pfu VSV-ova plus treated i.p. with 100 µg FGK4.5 one day post infection. Ninety days after primary challenge mice were re-challenged with 5×10⁴ cfu LM-ova. Seven days later the sensitivity to antigen and functionality of the secondary effector CD8⁺ T cell response was assessed by intracellular cytokine staining. Spleen lymphocytes were stimulated with one to 0.00001 µg/mL of the SIINFEKL peptide. Cells were fixed and rendered permeable before staining with antibodies IFNγ, TNFα, and IL-2. We tested (A) the percent IFNγ and (B) the percent IFNγ over the maximum; at all peptide dilutions. Next we analyzed the (C) geometric mean fluorescence intensity (MFI) of the CD8⁺ T-cells for IFNγ, the (B) percent of IFNy expressing cells also expressing TNFα and (E) the IFNγ expressing cells also expressing IL-2. Results shown for 0.001 and 1 µg/mL SIINFEKL only (Figures C, D, E). Statistical significance was determined using a one-way ANOVA with a Bonferroni’s post-test ***p<0.001**p<0.01; *p<0.05). Each group contained 4–5 mice per group.