CD44^hiCD8⁺ and CD44^loCD8⁺ T cells are generated from a common precursor pool. (A) CD44^hiCD8⁺ and CD44^loCD8⁺ T cells were isolated from naive C3H.SW mice by the combination of magnetic cell sorting and FACS. B6 mice were irradiated and injected with C3H.SW T^–BM, with or without CD8⁺ T cells. Survival of B6 mice after BMT: ♦, T^–BM (n = 20); ▪, T^–BM plus CD44^hiCD8⁺ (n = 17); ▴, T^–BM plus CD44^loCD8⁺ (n = 17); ×, T^–BM plus unstimulated CD8⁺ (n = 35); *P < .01 (▪ vs. ▴ or ×). Data shown here are pooled from at least 4 independent experiments. (B) Separated C3H.SW CD44^loCD8⁺ naive T cells were cultured in the presence of B6 DCs. Five days later, B6 DC-induced CD44^hiCD8⁺ and CD44^loCD8⁺ T cells were sorted from the DC-induced cultures and transplanted together with C3H.SW T^–BM into lethally irradiated B6 mice. Survival after BMT: ♦, T^–BM (n = 8); ▪, T^–BM plus CD44^hiCD8⁺ (n = 12); ▴, T^–BM plus CD44^loCD8⁺ (n = 16). P < 0.01 (▪ versus ▴). Data shown here are pooled from 2 separate experiments.