The ratio of total CD8+/total CD4+ of human CD45+ cells was found to be 0.56 ± 0.28 in HD PBMCs, 1.08 ± 1.49 in the PBMCs of the mice transplanted with HD-PBMCs (HD-M), 0.42 ± 0.31 in BC PBMCs, and 0.41 ± 0.51 in the PBMCs of the mice transplanted with BC-PBMCs (BC-M). This evidence concerns the gene CD8A and breast cancer.