The proportion of CD8+T cells in tumor tissue of mice fed with probiotics (Bifidobacterium) was significantly higher than that of mice fed with nonprobiotics, and it was also found that T cell immunoglobulin mucin-1 (TIM-1), a costimulatory molecule of T cell, was highly expressed, while PD-1 was downregulated, and interferon-gamma (IFN-γ)+CD8+TIL and tumor necrosis factor-α (TNF-α)+CD8+TIL were also increased. Here, PDCD1 is linked to neoplasm.