PRF1 and neoplasm: In addition, after tumor rechallenge, the expression levels of IFN-γ, perforin, and granzyme B in CD8+ T cells in cryo-thermal treated mice were significantly increased, and they were significantly decreased with depletion of CD4+ T cells, but only perforin and granzyme B in CD8+ T cells were significantly decreased with depletion of CD8+ T cells (Figure 2B).