Survival of BALB/c hosts transplanted with donor C57BL/6 TCD BM cells with or without total T cells or T-cell subsets. (A) Lethally irradiated (800 cGy) hosts were given 2 × 10⁶ TCD BM cells from donors with or without (n = 12) 0.5 × 10⁶ sorted donor total T cells (n = 10) or total CD4⁺ T cells (n = 10) from the spleen. The data were pooled from 2 independent experiments. (B) Serial measurements of body weights were determined in mice from panel A. ⁺Weight measurements were stopped when no more than 2 mice remained in the group. (C,E) The hosts received 500 BCL₁ lymphoma cells 6 hours after irradiation. Lethally irradiated hosts were given 2 × 10⁶ TCD BM cells with or without (n = 8) 0.5 × 10⁶ sorted CD62L^hiCD44^lo naive (n = 10) or CD44^hi memory phenotype CD4⁺ or total T cells (n = 10). Control untreated hosts were also given tumor cells (n = 8). The data were pooled from 2 independent experiments. (D,F) Representative 2-color flow cytometric analyses of CD19 versus BCL₁-idiotype markers in the peripheral blood from recipients with progressive tumor growth in panels C and E, respectively, are shown 28 days after transplantation of TCD BM alone or with memory CD4⁺ T cells or memory total T cells, respectively.