CD1D and neoplasm: NKT cells not only show NK cell features such as expression of CD56, Fc receptor CD16, and granzyme production, but also display αβ-TCR to recognize both endogenous and exogenous lipid antigens presented on CD1d, a non-classical antigen-presenting molecule resembling MHC class I. CD1d is expressed on APCs, epidermal keratinocytes, hepatocytes, adipocytes, thymocytes, and is downregulated in tumor cells (50).