Contrary Roles of IL-4 and IL-12 on IL-10 Production and Proliferation of Human Tumour Reactive T Cells

The cytokine profile of tumour reactive T cells is likely to play a central role in their function. However, little is known about how cytokine patterns of tumour reactive T cells can be regulated. Here, the authors investigated the influence of exogenous regulatory cytokines in addition to interleukin-2 (IL-2) on cytokine patterns and the proliferation of T cells recognizing an autologous sarcoma cell line. In this system, IL-4 and IL-12 showed the most polarizing influences on tumour reactive T cells. Exogenous IL-4 induced a predominant production of IL-4 while decreasing the interferon-γ (IFN-γ) and IL-10 production by tumour reactive T cells. It also stimulated the growth of tumour reactive CD4⁺ T cell clones. In contrast, IL-12 substantially increased the production of IL-10 and IFN-γ. This was accompanied by a growth inhibition of tumour reactive T cells. The growth of CD4⁺ tumour reactive T cells was also suppressed by exogenous IL-10. This study shows that cytokine patterns and proliferation tumour reactive T cells can be significantly influenced by exogenous cytokines and confirms the hypothesis of a negative feedback loop of IL-12 by the induction of IL-10 in the context of human tumour reactive T cells.