Allogeneic antitumor T lymphocyte persistence in vivo. C57BL/6 mice bearing B16 tumors were irradiated with 5 or 9 Gy TBI and injected on day 0 with 10⁶ allogeneic pmel-1^b/d cells, vaccinia virus encoding hgp100_25-33, and exogenous rhIL-2 (alloPVI) or with 10⁶ syngeneic pmel-1b/b cells, vaccinia virus encoding hgp100_25-33, and exogenous rhIL-2 (synPVI). All groups received syngeneic BMT with 10⁶ unsorted bone marrow cells the day after the transfer of the effector cells. At the indicated time points, mice were killed, and the spleens were analyzed by flow cytometry for the presence of the transferred cells. (A) The dot plots show the percentage of CD8⁺ H-2 D^d+ cells. Allogeneic cells were detectable up to day 24 after transfer. (B) Absolute numbers of CD8⁺Vβ13⁺ cells present in the spleens of the animals. Each bar represents 3 mice plus or minus SE. Data are representative of 3 independent experiments.