Our present study indicated that APN deficiency conferred a higher frequency of CD8+IFN-γ+ T cells in the spleen and lymph nodes, as well as higher levels of IFN-γ, perforin, and TNF-α and lower levels of IL-10 in the serum of rhabdomyosarcoma-bearing mice. The gene discussed is PRF1; the disease is rhabdomyosarcoma.