Fig. 1.

Proliferation and phenotypic conversion of naïve CD8⁺ T cells in a lymphopenic host. A total of 2 × 10⁶ naïve OT-I T cells were sorted (CD8⁺CD44^lo) and transferred i.v. to irradiated (600 rad) or unirradiated B6 hosts. (A) Sorted cells were CFSE-labeled before transfer. After 6 days, splenocytes were analyzed by flow cytometry. CFSE levels are shown for CD8⁺CD45.1⁺ gated cells transferred to irradiated (filled histogram) or unirradiated (open histogram) hosts. (B) CD8⁺Thy1.1⁺ splenocytes recovered from irradiated hosts were analyzed by flow cytometry for expression of CD44 and Ly6C expression.