Tumor cells release many kinds of immunosuppressive and pro-inflammatory factors that facilitate tumor immune escape and tumor growth. In addition, many kinds of immunosuppressive cells accumulate in the tumor microenvironment. These factors are ultimately responsible for orchestrating immunosuppressive network at the tumor site. CD1d-restricted invariant natural killer T (iNKT) cells play crucial roles in both the innate and acquired immune responses. Activation of iNKT cells leads to downstream activation of other cell types in the immune system, which is crucial to the protective anti-tumor immune responses. In this review, we discuss the contribution of iNKT-dendritic cell (DC) cross-talk governing T helper (Th) balance and the possible mechanisms by which NKT cells regulate the tumor microenvironment to enhance the anti-tumor immune responses.
