Bone marrow–derived lymphocytes are not necessary for allogeneic effector cell rejection. (A) C57BL/6 mice bearing B16 tumors were irradiated with 9 Gy TBI and injected on day 0 with 10⁶ allogeneic pmel-1^b/d cells, vaccinia virus encoding hgp100, and exogenous rhIL-2 (alloPVI) or with 10⁶ syngeneic pmel-1^b/b cells, vaccinia virus encoding hgp100, and exogenous rhIL-2 (synPVI). On the day after cell transfer, the mice received syngeneic BMT with 10⁶ unsorted bone marrow cells derived either from wild-type animals (wt BM) or Rag1^−/− (Rag1^−/− BM) animals. Results of tumor area are the mean of measurements of at least 5 mice per group (± SEM). Data are representative of 2 independent experiments. (B) After 30 days, mice that received allogeneic effector cells were killed, and the spleens were analyzed by flow cytometry for the presence of the transferred cells. Allogeneic CD8⁺ H-2^d+ cells were undetectable at day 30 in both allogeneic PVI groups independently of the type of bone marrow cells they received.