Oral malignancy, a very common disease with high incidence in humans, poses great threats to human health and life. The activating receptor natural killer group 2 member D(NKG2D) and its ligands play important roles in the immune response to oral tumors by initiating innate immune surveillance and immune clearance at the early stage of tumorigenesis. Two types of ligands have been observed, namely, major histocompatibility complex 1 class-related molecule A and B and UL16-binding protein. Extensive studies on the function of NKG2D and its ligands in oral tumor immunity are helpful in discovering new approaches against oral cancer. This review presents research progress on the immunoregulatory effects of NKG2D receptor and its ligands on oral tumors.
