Objective: Our aim was to investigation the roles of MHC class I chain-related gene A(MICA) and naturalkiller cell group 2D(NKG2D) in human renal cancer cells. Materials and Methods: The expression of membraneMICA (mMICA) on renal cells and NKG2D on NK cells were detected by flow cytometry (FCM); the contentof sMICA were detected by enzyme linked immunosorbent assay (ELISA) and the distribution of mMICA onrenal tumor tissues by immunohistochemistry; the interaction between MICA and NKG2D was observed byantibody closed method. Results: Our results showed that the expression of mMICA in renal cancer tissues wassignificantly higher than in controls, where the soluble MICA was not expressed. Cytotoxic activity of NK cellswas significantly reduced after exposure to NKG2D and MICA antibodies (P<0.05), and serum containing sMICAcan obviously lower the function of NKG2D (P<0.05). Conclusions: The interaction of mMICA and NKG2Dplay important roles in mediation of cytotoxicity of NK cells in RCC. On the other hand, sMICA may mediatetumor immune escape through down- regulated NKG2D expression.
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