Figure 2

Immunization of HER2/neu transgenic mice with Hp91 in nanoparticles increases CTL responses. (A) HER2/neu transgenic mice at 2 months of age were immunized with 5 μg HER2 peptide in PBS, or with 25 μg Hp91 free peptide or the same amount of Hp91 packaged within PLGA-NPs. (B) A different group of HER2/neu transgenic mice was immunized at 4 months of age with 20 μg HER2 free peptide or 4.5 μg HER2 peptide inside PLGA-NP in PBS, alone or in combination with 250 μg Hp91 free peptide or 14 μg Hp91 in PLGA-NPs. (A and B) Eight days after the final immunizations, mice were sacrificed and expanded splenocytes were cultured in the presence of HER2 peptide in an IFN-γ ELISPOT assay. CTL responses were determined 18 h later by quantifying the number of IFN-γ spot-forming cells using an automated ELISPOT reader. Data shown represents the means (± standard error of the mean (SEM)) for five mice per group. ^*Indicates statistical significance P <0.05. CTL, cytotoxic T lymphocyte; ELISPOT, enzyme-linked immunospot; HER2, human epidermal growth factor receptor 2; IFN-γ, interferon gamma; PBS, phosphate-buffered saline; PLGA-NPs, poly(D,L-lactic-co-glycolic) acid nanoparticles.