Protective and therapeutic antitumor immunity requires allogeneic cell transplantation, and CD4⁺ and CD8⁺ T cells in DLI and autologous tumor cell vaccination.

(A) Scheme of experiment in panel B. (B) Protective antitumor immunity requires NST and posttransplantation vaccine. BALB/c mice underwent NST from B10.D2 donors. Beginning 2 weeks after transplantation, chimeras then received nothing (▾), 20 million B10.D2 splenocytes intravenously (▿), or 20 million B10.D2 splenocytes and 4T1 tumor vaccine (▪; N = 5 per group), as shown in panel A. Four months later, all mice that received transplants, and groups of 5 untreated (●) or vaccinated BALB/c controls (○), were challenged with 10⁴ 4T1 cells intravenously. Tumor-free survival is plotted as a function of time after intravenous tumor challenge. (C) Scheme of experiment in panel D. (D) Therapeutic antitumor immunity requires CD4⁺ and CD8⁺ T cells in the DLI. BALB/c mice bearing 13-day-old 4T1 tumors received surgery and NST from B10.D2 donors as illustrated in Figure 2A. On day 28, mice received 2 × 10⁷ B10.D2 splenocytes, either unmodified (●, ○) or depleted of CD4⁺ (▾) or CD8⁺ (▿) T cells. Three days later, mice received 4T1 vaccine (●, ▾, ▿) or nothing (○). Tumor-free survival was then monitored. (E) Therapeutic antitumor immunity requires autologous cells in the vaccine. Tumor-bearing BALB/c mice received surgery, NST, DLI, and vaccine consisting of the bystander line mixed with nothing (▾), irradiated 4T1 cells (●), irradiated DA-3 cells (○; a BALB/c breast cancer), or irradiated NT-2 cells (▿; a mammary cancer of FVB/N [H-2^q] mice). Tumor-free survival is plotted as a function of time after tumor injection.