IL-18 retains a perforin-dependent GVL effect.

(A) B6D2F1 mice were injected with IL-18 or diluent, given 13 Gy TBI, and received transplants of allogeneic or syngeneic BM and T cells as in Figure 1. All animals were also injected intravenously with 2000 P815 tumor cells on day 0. (Allogeneic: control treated, ●, n = 8 and IL-18 treated, O, n = 8 or syngeneic: control treated, ■, n = 8 and IL-18 treated, ▪, n = 8 donors).^★P < .03 for O, allo IL-18 versus ●, allo control. Data from 1 of 2 similar experiments are shown. (B) Lethally irradiated (13 Gy) B6D2F1 mice received transplants of 5 × 10⁶ TCD BM from wild-type B6 (H2^b) and 2 × 10⁶ splenic T cells from allogeneicpfp^−/− B6 (H2^b) donors. Survival in control (●, n = 8) and IL-18–treated (○, n = 8) recipients of T cells from pfp^−/− donors was significantly different. ^★★P < .01, ○ versus ●. (C) B6D2F1 mice underwent transplantations as above and injected intravenously with 2000 P815 cells on day 0. All syngeneic (▪, n = 10), allogeneic control (●, n = 10), allogeneic IL-18–treated pfp^−/− T cells (○, n = 10) and allogeneic IL-18–treated wild-type T cells (■, n = 10) survived. P = NS, ○ versus ●; andP < .04, ■ versus ○.