Figure 2.

SA-4-1BBL conjugate vaccine has improved immunostimulatory activity than nonconjugate vaccine. A, in vivo OT-I and OT-II proliferation. 2×10⁶ sorted OT-I T and OT-II T cells (CD45.2⁺) were labeled with CFSE and injected i.v. into naïve congenic C57BL/6.SJL (CD45.1⁺) mice. Twenty-four h later mice were vaccinated s.c. with Ova (10 μg) conjugated or nonconjugated to various doses of SA-4-1BBL as indicated. Proliferation was assessed 3 days after vaccination by gating on CD4⁺CD45.2⁺ and CD8⁺CD45.2⁺ cells using flow cytometry. Data is representative of four independent experiments. B, as in A, but flow sorted OT-I T cells were injected into 4-1BB^-/- mice and OT-I T cell proliferation was assessed by gating on Vβ_5.1/5.2⁺CD8⁺ T cells. Data is representative of two independent experiments. C, in vivo endogenous CTL killing response. C57BL/6 (CD45.2⁺) mice were immunized s.c. with Ova (50 μg) conjugated or nonconjugated with SA-4-1BBL (25 μg). Seven days post vaccination, mice received SIINFEKL-pulsed syngeneic splenocytes from C57BL/6.SJL (CD45.1⁺) and peptide-specific killing was assessed 2 days later and expressed as percent lysis for each histogram (n = 5; * P < 0.05 compared with each other and Ova control). D, as in C, but mice were immunized with a recombinant HPV-16 E7 protein (10 μg) conjugated or nonconjugated to SA-4-1BBL (25 μg). n = 5, * P < 0.05 compared with each other and E7 control.