Figure 3.

The role of polyamines in both innate and adaptive immune responses in cancer Polyamines and their key enzymes can reshape the tumor immune microenvironment through a variety of transcription factors or cytokines, even have dual roles. The polyamine-eIF5A-hypusine axis regulates macrophage polarization, especially polyamines tend to promote the polarization of M2-type macrophages. Polyamines also negatively regulated the functions of DC cells, NKT cells, CD8+ TILs and Th1 cells, and positively regulated the functions of Treg cells. For NK cells, polyamines are a double-edged sword. In fact, the tumor immune microenvironment is mutually influenced and restricted by a variety of factors. The regulation of polyamines in regulating the function of immune cells is not absolute, which will change according to the changes of tumor immune microenvironment.