Allogeneic tumor-specific CD4⁺ cells cause tumor regression and ocular autoimmunity in lethally irradiated hosts. C57BL/6 mice bearing B16 tumors established for 12 days were irradiated with 9 Gy TBI. Mice were left untreated as a control (NT) or injected on day 0 with 10⁶ allogeneic TRP-1^b/d cells and exogenous IL-2 (AlloTI) or 10⁶ syngeneic TRP-1^b/b cells and exogenous IL-2 (SynTI). All groups received syngeneic BMT with 10⁶ unsorted bone marrow cells the day after the transfer of the effector cells. (A) Spleens analyzed for the presence of transferred T cells at the indicated time points. The experiment was independently repeated with similar results. (B) B16 tumor growth in the different treatment groups. Results of tumor area are the mean of measurements of at least 5 mice per group (± SEM) (n = 5, 9, and 10 mice for NT, AlloTI, and SynTI, respectively, in the experiment shown). Data are representative of 3 independent experiments. (C) Hematoxylin and eosin staining of ocular tissue of mice killed at day 14. Images were obtained using a Nikon Eclipse E400 microscope equipped with Nuance Multispectral Imaging System VIS (original magnification ×100). Images were processed using Adobe Photoshop, version 7, as described in “Histology.”