FasL-mediated killing is not required for CD4 GVL. B6 mice were irradiated and reconstituted with T-cell-depleted C3H.SW BM, wild-type, or Fas^lpr Mp210/NGFR infected progenitors, with or without 4 × 10⁶ C3H.SW CD4⁺ T cells. (A) Survival. (B) Fas expression. Note Fas expression in wild-type but not Fas^lpr NGFR⁺ cells.