Histopathological examination of the liver obtained from normal BDF1 and the recipients of B6 TCD-BM, B6 BM, or B6 BMS in the GVL experiment shown in Fig 3A. (A) Liver section from an age-matched normal BDF1 mouse. (B) Massive leukemia cell infiltration was observed in the liver section from the recipients of B6 TCD-BM at the time of death. (C) Liver section obtained from the recipients of B6 BM on day 28 after BMT showed residual leukemia cells among normal liver tissue. (D) Liver section from the recipients of B6 BMS on day 28 after BMT showed severe mononuclear cell infiltration, but there was no residual leukemia cell in any fields of the section. Each figure shows a representative of three similar experiments. Similar results were also observed by using another tumor P815 cells. Original magnification × 400.