Fig. 3.
Cross-priming with Ova-adsorbed, biodegradable PLGA microspheres followed by short-interval booster immunization quickly generates robust Ova257-specific CD8 T cells. (A) Adsorbed Ova protein on the surface of PLGA microspheres was detected with Ova-specific antibody by flow cytometry before mice were immunized (shaded histograms: isotype controls). (B–D) Naïve B6 mice were immunized with ∼109 (B and D) or different (C) doses of Ova-adsorbed PLGA microspheres (∼109, ∼108, ∼107, or ∼106) or with ∼109 BSA-adsorbed PLGA microspheres as control and were analyzed at day 7 after priming (B) for Ova257-specific CD8 T cells by mouse IFN-γ ELISPOT assay or were boosted i.p. with either (C) virLM-Ova (∼105 cfu/mouse) or (D) 500 μg full-length Ova protein plus poly(I:C) (100 μg) plus anti-CD40 mAb (clone 1C10). C and D show kinetics of Ova257-specific CD8 T-cell response in PBL as detected by Kb/Ova257 tetramer staining (mean frequency ± SEM, n = 4). *Statistical analysis was performed using an unpaired, two-tailed t test.