Figure 3.

Immunization with Lm-HMW-MAA-C induces effector CD8⁺ T cells in C57Bl/6 and HLA-A2/K^b transgenic mice. A, CD8⁺ T cells from C57Bl/6 mice vaccinated with Lm-HMW-MAA-C inhibit the growth of B16F10-HMW-MAA tumors in vivo. CD8⁺ T cells were purified from the spleen of either naïve or Lm-HMW-MAA-C immunized mice and mixed to B16F10-HMW-MAA tumor cells at a 10:1 effector to target ratio. The mixed cells were injected subcutaneously in mice (8 per group), which were followed-up for 28 days and examined every 2 days for tumor growth. B, vaccination of HLA-A2/K^b transgenic mice with Lm-HMW-MAA-C induces a CD8⁺ immune response against the HLA-A2-restricted HMW-MAA_2238–2246 epitope. C57BL/6 and HLA-A2/K^b transgenic mice were either immunized twice at one-week interval with Lm-LLO-HMW-MAA-C or left untreated. One-week later the spleens were harvested and analyzed for IFN-γ secretion upon stimulation with the HMW-MAA_2238–2246 peptide (LILPLLFYL). Values are expressed as spot-forming cells (SFC) ± SEM. C, HLA-A2/K^b transgenic mice were immunized once with Lm-HMW-MAA-C. Spleens were harvested 9 days later and IFN-γ production by CD8⁺ T cells was analyzed upon stimulation with the HMW-MAA_2238–2246 peptide for 5 hours in the presence of monensin. Cells were gated on CD8^high and analyzed for intracellular IFN-γ. *, P ≤ 0.05, Mann-Whitney test.