PRF1 and neoplasm: These FcγRIIlow/neg B cells exhibited a noteworthy ability to spontaneously produce IL-10 ex vivo that could suppress the expression of cytotoxic granzyme B and perforin, as well as the pro-inflammatory cytokines such as tumor necrosis factor-α and IFN-γ, in autologous tumor-derived CD8+ cytotoxic T cells [49].