Survival curve and leukemic-tumor-burden in dose-reduction transplantation with bulk splenocytes. C57BL/6-DBA2 F1 recipients were transplanted with 2 × 104 P815 leukemic cells expressing luciferase (H-2d), 5 × 106 TCD-BM (H-2b), and 1 × 107 WT-SP or KO-SP (H-2b). Then, the dose of bulk splenocytes was reduced to 5 × 106, 5 × 105, and 5 × 104. Open squares, filled squares, and filled triangles indicate transplantations without splenocytes, with WT-SP, and with KO-SP, respectively. Right panels indicate the average of signal intensity of luminescence in survivors at indicated days after transplantation, which correlates with leukemic-tumor-burden. Empirically determined positive-negative threshold indicated in broken line was 106 relative signal intensity per mouse.