CD4 and neoplasm: Our RM1 tumors constitutively express IL-18 locally in the tumor resulting in the observed influx of CD4+ T cells, CD8+ T cells and macrophages into the tumors, while the Osaki et al. model used intraperitoneal injection of IL-18 which is less likely to induce local tumor effects but more likely to induce systemic effects, in this case NK cell activation.