Multiple IVS amplifies CTL response and IFN-γ release.

(A) Tg mice were vaccinated with 100 nmol of K25V fusion peptide as described in the legend to Figure 1 and boosted 2 weeks later with an additional 100 nmol of the identical peptide. Mice (n = 8) were killed after 2 weeks, spleens removed, and either one (●) or 2 (⋄) IVSs were performed followed by a CRA as described in “Materials and methods.” Values represent subtraction of nonspecific (p53_149-157) from specific (pp65_495-503) cytotoxicity of peptide-sensitized T2 cells as described in “Materials and methods.” (B) Aliquots of culture medium (200 μL) from IVS cultures (●, 1 IVS and ⋄, 2 IVSs) from mice immunized as described for panel A were withdrawn at the indicated times, and IFN-γ protein was measured from the undiluted fluid by ELISA as described in “Materials and methods.” The detection limit of the assay was established as 70 pg/mL using IFN-γ protein standard (Pharmingen).