Immunization with Embryonic Stem Cells/Induced Pluripotent Stem Cells Induces Effective Immunity against Ovarian Tumor-Initiating Cells in Mice

Figure 6

Vaccination with lysates of mESCs/mIPSCs generated lymphocytes that selectively target CSCs. (a, b) Targeting of CSCs and non-CSCs by mESCs/mIPSCs-primed CTLs. After 4 hr of incubation, the lytic activity of the splenocytes against target cells (CD133-positive and CD133-negative ID8 cells) was assessed using effector-to-target cell ratios of 25 : 1, 50 : 1, and 100 : 1. The killing of CSCs and non-CSCs mediated by CTLs was assessed using an LDH release assay. A higher percentage of cytotoxicity suggests a greater degree of cell lysis. (c) Complement-dependent cell lysis of CD133-positive cells was tested individually in serum from immunized mice. The CytoTox96 Nonradioactive Cytotoxicity Assay was used to assess the lysis of CD133-positive and CD133-negative ID8 cells. (d, e) Mouse splenocytes were assessed for the presence of T cells capable of secreting interferon- (IFN-) γ in response to CD133-positive and CD133-negative ID8 cells using an IFN-γ ELISPOT kit. ( , , and , error bars represent standard deviation. Statistical analysis was performed using Student’s t-test or one-way ANOVA).

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