Figure 5. Induction of IFN-γ production by CD4⁺ T is not prevented by CTL-mediated DC killing.

C57BL/6 mice were injected with CD45-congenic OT-II CD4⁺ T cells; OT-I CTL were injected in some of the mice at the same time. 24 h later, mice were immunized s.c. with DC loaded with different forms of OVA. 19 days after immunization, spleens were collected and the total number of OVA-specific, IFN-γ-producing CD4⁺ T cells was determined by intracellular staining. Bar graphs show mean+SEM. (A) Mice were immunized with WT or MHCII^−/− DC loaded with OVA protein (2 mg/ml). The bar graph shows data from one of two similar experiments, each with 5 mice per group, that gave similar results. (B) Mice were immunized with OVAtg DC. Results are from 5 mice per group. (C) Mice were immunized with WT or MHCII^−/− DC loaded with OVA protein (2 mg/ml); some of the DC were also treated with Ptx. The bar graph shows data from 5 mice per group.