Reduction of GVHD and preservation of GVL activity. (A) Experimental protocol. BDF1 recipients received TBI (9 Gy) followed by intravenous injection of TCD B6 bone marrow cells (5 × 10⁶) and P815 cells (10⁴) on day 0. In addition, some recipients received B6 spleen cells (2.5 × 10⁷) on day 0. BDF1 recipients that received TCD B6 bone marrow cells without P815 cells were used as BMT controls. BDF1 recipients that received TCD B6 bone marrow cells and B6 spleen cells without P815 cells were used as GVHD controls. HVJ liposomes containing 8 μg human HGF cDNA or a mock vector were injected intramuscularly on days 0, +7, +14, and +21 of BMT. (B) The survival of HGF-treated GVHD recipients was significantly better than that of all other groups. Shown are BMT controls (▿, n = 5); GVHD controls (▵, n = 5); P815-injected BM transplant (control treated) (○, n = 5); P815-injected BM transplant (HGF treated) (▪, n = 5); P815-injected GVHD (control treated) (□, n = 10); P815-injected GVHD (HGF treated) (▪, n = 10). ^*P < .01 for survival of P815-injected GVHD (control treated) versus P815-injected GVHD (HGF treated). Representative data from 2 similar experiments are shown.