Killing from within.

Interleukin-10 (IL-10) is considered to be an immunosuppressive cytokine. However, the continuous administration of pegylated IL-10 (PEG-IL10) leads to the rejection of large, firmly established and metastatic syngeneic tumors. PEG-IL10 therapy induces the expansion and activation of intratumoral, tumor antigen-specific CD8(+) T cells, leading to interferon γ (IFNγ)-mediated Th1 like immunity and tumor rejection.