Dendritic Cells (DC) play a pivotal role in the initiation of T-cell-mediated immune responses, making them an attractive cellular adjuvant for use in cancer vaccines. The interaction of T cell with DC is crucial for directing T cell differentiation towards the Th1, Th2 or Th17 type, and several factors determining the direction of the T cell polarization. IL-12 plays a central role in the immune system, not only by augmenting the cytotoxic activity of T cells and NK cells and regulating IFN-γ production, but also by the capacity of IL-12 to promote the development of Th1. Some plant-derived terpenes regulate differentiation of DC from human monocytes. Terpene compounds-primed DC enhances the differentiation of naive T cell towards the Th1 type, which is dependent on IL-12 secretion. Some patents on terpene compounds, which may lead to the development of effective immunotherapy for cancer, are also discussed in the review.