H60-reactive T_M expand after transplantation into H60⁺ recipients without CD4 help. (A) Expansion of LTFNYRNL-reactive CD8 cells requires the host to be H60⁺. B6.H60 or B6 (H60⁻) mice were irradiated and reconstituted with C3H.SW BM with 10⁶ CD8 cells from unmanipulated or H60-vaccinated C3H.SW donors along with 10⁵ CD4 cells from unmanipulated C3H.SW mice. (A) Representative flow cytometry. (B-C) B6.H60 mice were irradiated and reconstituted with C3H.SW BM with 2 × 10⁵ C3H.SW T_MH60 with or without graded numbers of CD4 cells from unmanipulated C3H.SW mice. (B) Representative flow cytometry of splenocytes at day 7 after transplantation, with gating on CD8⁺ cells. Tet^H60 binding and IFN-γ staining after LTFNYRNL stimulation are shown. (C) The total numbers of Tet^H60+ and percentages of IFN-γ⁺ CD8 cells are shown. P > .1 comparing T_MH60 with T_MH60 plus any CD4 dose. Data are representative of 2 independent experiments.