Fig. 6.

Both CD4⁺ and CD8⁺ T cells are required for long-term immunity to NB in mice treated by combination immunotherapy. a Mice surviving after combination IT were re-challenged iv with a tumorigenic dose of Neuro2a/pc cells, 150 days after the first NB implant (*p = 0.0031 vs challenge in naïve untreated mice). Mice receiving anti-CD8 or anti-CD4-cell-depleting antibodies showed no immunity to NB cell re-challenge compared to mice receiving irrelevant mAb (*p = 0.0023 and p = 0.015, respectively). Percentages of tumor-free mice are indicated on the y-axis, and the fraction of tumor-free mice of each group is given in brackets. b Percentages of CD8⁺ CD44^high memory T cells in spleen cells from naïve, untreated NB-bearing and long-term cured mice assessed by immunofluorescence analysis. Data (mean and SD) refer to groups of three mice (p < 0.05 between cured mice and the other groups). c Percentages of CD4⁺ CD44^high memory T cells (Mean ± SD) in spleen cells from naive, untreated NB-bearing and long-term cured mice assessed by immunofluorescence analysis (p < 0.05 between cured mice and the other groups)