Tumor regression and minor GVHD-like incidences in J15 TCR Tg systems might be due to super-physiological numbers of H60-cognate escapee J15 T cells because the numbers of H60-cognate polyclonal escapee CD8 T cells were far lower than those of J15 escapee CD8 T cells in the spleens of Con-H60 recipients (i.e., 72 versus 1.5 × 105, respectively). This evidence concerns the gene CD8A and graft versus host disease.