Enhanced survival of B10.BR mice transplanted with C57.BL6 BM cells and irradiated C57.BL6 splenocytes depended on the presence of splenic T cells. Data are pooled from 3 experiments in which groups of 8 to 10 B10.BR mice were irradiated with 10 Gy on day −2 and transplanted with 0.5 × 106 C57.BL6 allogeneic BM cells and splenocytes or 0.5 × 106 syngeneic B10.BR BM cells on day 0. Allogeneic splenocytes were prepared daily from C57.BL6 mice, TCD, or TCE, as described in Materials and Methods, and irradiated to 7.5 Gy immediately before injection on days −1, 0, and +1. One group of 5 B10.BR mice received syngeneic B10.BR BM (▪▪ ▪); a second group of 25 B10.BR mice received a total of 75 × 106 C57.BL6 irradiated splenocytes with C57.BL6 BM (▪▪); a third group of 16 B10.BR mice received C57.BL6 BM alone (____); a fourth group of 25 B10.BR mice received a total of 60 × 106C57.BL6 TCD irradiated splenocytes with C57.BL6 BM (–— –); a fifth group of 29 B10.BR mice received a total of 15 × 106 C57.BL6 TCE irradiated splenocytes with C57.BL6 BM (▪▪▪); and a sixth group of 15 mice received a total of 75 × 106 nonirradiated C57.BL6 splenocytes with C57.BL6 BM (– – –). A significantly superior survival was found for both the groups of mice receiving multiple infusions of irradiated allogeneic splenocytes and the group receiving TCE irradiated allogeneic splenocytes compared with the group that received nonirradiated splenocytes (P < .01); the group that received TCD allogeneic splenocytes (P ≤ .01); and the group that received syngeneic BM (P < .05).
