Vaccination during immune reconstitution effectively sustains tumor-specific T-cell activation in tumor-bearing recipients.

BALB/c were challenged intravenously with 1 × 10⁶A20HA cells or remained tumor-free. Ten days later, all mice were irradiated and transplanted with a graft as described in Figure 5. Mice were vaccinated with 1 × 10⁶ irradiated A20HA/GM-CSF cells subcutaneously in the left flank on the days indicated and were killed for analysis 21 days (A and B) or 42 days (C and D) post-BMT. Three mice were included per group for each time point. (A and C) Percentage of HA-specific CD4⁺ TCR clonotype-positive T cells as analyzed by 2-color flow cytometry. (B and D) γ-IFN production in response to a 48-hour incubation with HA peptide, as measured by ELISA. Values are the mean + SE. Values for T cells cultured in the absence of HA peptide were below the limit of detection for the ELISA kit.