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The powerful activating receptor NKG2 D is expressed by natural killer ( NK) cells and promotes cytotoxic lysis of cancer cells expressing NKG2D ligands (NKG2D-Ls). We report the effective induction of NKG2 D- Ls, achieved with the naturally occurring polyphenol resveratrol, in a broad range of leukemia cells. In this study, resveratrol upregulated the NKG2 D- Ls MHC class I chain-related proteins MICA and MICB, and UL16-binding proteins ULBP1, ULBP2, and ULBP3 in most of the leukemia cells analyzed. Ligand upregulation induced by resveratrol was impaired by pharmacological and genetic disruption of ataxia-telangiectasia mutated kinase, the main regulator of NKG2 D- L expression. Leukemia cells treated with resveratrol were more susceptible to killing by NK cells than untreated cells, and the enhanced cytotoxicity of NK cells was blocked by treatment of NK cells with anti- NKG2 D m Abs. Interestingly, resveratrol consistently upregulated the NKG2 D receptor expression and enhanced NKG2 D-mediated functions in resting NK cells obtained from healthy individuals. Therefore, resveratrol has attractive immunotherapeutic potential. [ABSTRACT FROM AUTHOR]