• cancer immune therapy;
  • CD8+ T cells;
  • cytotoxic T cells;
  • IFN-γ;
  • major histocompatibility complex;
  • pegylated-IL-10

Recently, the development of several strategies based on immunotherapy has raised hopes for a more promising way to treat cancer patients. Here, we describe how interleukin (IL)-10, a seemingly unlikely candidate, stimulates the immune system in a particularly efficacious way. IL-10, an omnipotent anti-inflammatory cytokine, delivers an equally potent immune stimulation in the context of CD8+ T cells and tumor immunity. By activation of tumor-resident, tumor-specific CD8+ T cells, pegylated IL-10 can induce rejection of large and metastasizing tumors in mice. Here, we summarize the mechanisms of action of IL-10, the reasons why the mechanisms may be crucial for the treatment of cancer patients, and the rationale for applying pegylated IL-10 in the clinic.