Amazing IL-9: revealing a new function for an "old" cytokine

Abstract

The incidence of melanoma - the most aggressive form of skin cancer - is dramatically increasing, while the development of innovative therapeutic strategies continues to be challenging, especially due to a lack of knowledge about the molecular mechanisms underlying melanoma progression as well as antitumor immunity. In this issue of the JCI, Yong Lu and colleagues report a central role for Th9 cells in antitumor immunity.

Figure 1. Effector functions of Th9 cells in antitumor immune responses.

Th9-derived IL-9 can have direct antitumor effects or can indirectly influence tumor growth by altering immune responses. IL-9 induces the production of CCL20 in lung epithelial cells, which mediates the recruitment of CCR6-expressing DCs and CD8⁺ CTLs. In addition, the MEA of IL-9 could further potentiate the induction of an adaptive antitumor immune response by providing mast cell–derived IL-1β and TNF-α. IL-9R, IL-9 receptor.