CpG1826 ODNs and imiquimod augment antitumor efficacy of allogeneic adoptive immunotherapy in full MHC-matched, mHAgs-mismatched chimeras. (Ai) Experimental schema; (ii) 4-week-old C3H.SW→B6 full chimeras (constructed using non-TCD BM) received DLI consisting of 2 × 107 C3H.SW splenocytes (▿), DLI plus 2 intraperitoneal injections of 1. 5 × 106 B6 (host)–derived ex vivo–generated BM DCs on days 0 and +7 (▪) or DLI plus CpG1826 on days 0, +3 and +7 (□). B6 mice that did not receive transplants served as a tumor control (Tm Control; ⋄). All animals (n = 9-11 per group) received an intravenous injection of 5 × 104 C1498 cells on day +35. An additional group of 4-week-old C3H.SW→B6 chimeras that received DLI + CpG but no tumor (no TM) served as DLI control (♦). Tumor-free survival was monitored thrice weekly and is plotted as a function of time after tumor inoculation in this and following experiments. Each experimental group was repeated at least twice with similar results. P < .02 (▿ versus ⋄; ▪ versus ▿), P < .001 (□ versus ⋄, ▿, ▪). (Bi) Experimental schema; (ii) 4-week-old C3H.SW→B6 full chimeras (constructed using non-TCD BM) were treated with imiquimod followed by nothing (▪), or DLI consisting of 2 × 107 C3H.SW splenocytes (♦). An additional group of animals was pretreated with vehicle prior to DLI administration (▿). Seven days later, all groups (n = 8-15/group) received an intravenous injection of 5 × 104 C1498 cells. A group of 5 B6 mice without transplants served as tumor control (⋄). This experiment has been repeated twice with similar results. P < .002 (♦ versus ▪). (Ci) Experimental schema; (ii) 4-week-old B6→B6 syngeneic chimeras (constructed using non-TCD BM) received DLI consisting of 2 × 107 B6 splenocytes (▾) or were pretreated with imiquimod prior to DLI administration (○). The 4-week-old C3H.SW→B6 full chimeras (constructed using non-TCD BM) pretreated with imiquimod prior to DLI served as allogeneic GVL control (♦). Seven days later, all groups received an intravenous injection of 5 × 104 C1498 cells. B6 mice that did not receive transplants served as tumor control (⋄). An additional group of 4-week-old C3H.SW→B6 chimeras that received DLI but no tumor served as DLI control (▪). Results of one representative experiment with 8 to 12 animals in each group. P < .002 (♦ versus ⋄, ○, ▾). (D) Synergistic triggering of TLR7 and TLR9 augments DLI-mediated GVL reactivity in 8-week-old full chimeras (constructed using non-TCD BM). (i) Experimental schema; (ii) C3H.SW→B6 chimeras received DLI alone (▿), were pretreated with anti-CD25 mAb on days −7 and −4 prior to DLI (▴), imiquimod on days −3 through +1 prior to DLI (♦) or were pretreated with imiquimod on days −3 through +1 prior to DLI and received CpGs ODN1826 on days 0, +3, and +7 (○). All chimeras were subsequently challenged with 5 × 104 C1498 leukemia cells 1 week after DLI. B6 mice that did not receive transplants served as tumor control (•). An additional group of 8-week-old C3H.SW→B6 chimeras that received DLI but no tumor served as DLI control ( × ). P < .01 (○ versus ▿, ▴, ♦).
