DC-induced C3H.SW CD44^hiCD8⁺ T cells induce lethal GVHD in gld.B6 mice. Highly purified C3H.SW CD44^loCD8⁺ T cells (CD45.2) were cultured in the presence of B6 DCs and IL-2 plus IL-15 for 5 days. Cells were collected and sorted into CD44^hiCD8⁺ and CD44^loCD8⁺ T-cell subsets. One million of these B6 DC-stimulated CD44^hiCD8⁺ or CD44^loCD8⁺ T cells were mixed with 5 × 10⁶ B6 T^–BM (CD45.1) and transplanted into lethally irradiated B6 mice. (A-B) Donor CD8⁺ T cells prior to their infusion or recovered from the spleens, LNs, and livers of B6 recipients at days 1, 7, and 14 following transplantation were stained with annexin V for flow cytometry analysis (A) and annexin V⁺ donor CD8⁺ T cells were calculated (B). The results shown are from one of 3 experiments. *P < .05 (mice receiving CD44^hiCD8⁺ T cells versus mice receiving CD44^loCD8⁺ T cells). (C) Unstimulated and DC-stimulated CD44^loCD8⁺ T cells at day 5 were stained with anti-Fas, anti-CD44, and anti-CD8 Abs followed by flow cytometry analysis. In panels A and C, the numbers represent percentages of each cell fraction. In panel B, the values represent means ± SD. (D-E) C3H.SW T^–BM (CD45.1, 7 × 10⁶), mixed with or without B6 DC-stimulated CD44^hiCD8⁺ or CD44^loCD8⁺ T cells (2 × 10⁶), was transplanted into lethally irradiated gld.B6 or wild-type B6 mice. The clinical GVHD signs and survival of these recipient mice were monitored. In panel D, ♦, T^–BM → gld.B6 mice (n = 6); ▪, T^–BM plus CD44^hiCD8⁺ → gld.B6 mice (n = 9); ▴, T^–BM plus CD44^hiCD8⁺ → B6 mice(n = 4). *P < .01 (▪ versus ▴). In panel E, ♦, T^–BM → B6 mice (n = 6); ▪, T^–BM plus CD44^loCD8⁺ → gld.B6 mice (n = 10); ▴, T^–BM plus CD44^loCD8⁺ → B6 mice (n = 12).