Figure 2

Improved efficacy of the mGC8 tumor cell vaccine when combined with lymphopenia and reconstitution. (A) LRAST treatment schema. One day after lymphopenia induction (cyclophosphamide, 200 mg/kg, i.p.), C57BL/6 mice were reconstituted by i.v. injection with 2 × 10⁷ splenocytes from naïve mice and vaccinated s.c. with 10⁷ irradiated mGC8 cells and GM-CSF/IFA. Two weeks after vaccination, mice were challenged with 3 × 10⁶ live mGC8 tumor cells and tumor growth was monitored. (B) Subcutaneous tumor growth of mice vaccinated with mGC8/IFA alone, with mGC8 and GM-CSF/IFA, with mGC8 and GM-CSF/IFA after induction of lymphopenia and reconstitution with spleen cells (LRAST), or the latter treatment without tumor vaccination (LP + GM-CSF/IFA) (n = 5 per group). The number of mice that developed a subcutaneous tumor within 50 days is indicated per group. (C) Tumor-free survival of the groups described in B and of another control group without tumor vaccination: GM-CSF/IFA. Tumor-free survival of LRAST-treated mice was significantly improved compared with mice vaccinated with mGC8 alone (p = 0.045). Tumor-free survival of LRAST- and mGC8 GM-CSF/IFA- treated groups was significantly different from the control group LP GM-CSF/IFA (p = 0.002 and p = 0.045, respectively), (n = 5 per group). (D) Tumor-free survival of all protected mice from experiment 2B/2C after rechallenge with s.c. injection of 3 × 10⁶ live mGC8 cells at day 60 and of a new control group without vaccination. The data also include two protected mice of Figure 1B that were rechallenged with live mGC8 at day 80 after mGC8 vaccination. (LRAST, n = 3; mGC8 GM-CSF/IFA, n = 2; mGC8, n = 3; no vaccine, n = 3). LP, induction of lymphopenia followed by reconstitution with spleen cells.