ABSTRACT
AIM: To study the effects of recombinant soluble MHC class Ⅰ chain-related protein A (sMICA) on the cytotoxicity, secretion of IFN-γ, proliferation and apoptosis of peripheral NK cells. METHODS: After NK cells were cocultured with recombinant soluble MICA proteins overnight, the cytotoxicity of NK cell on target cells was detected by flow cytometry. The supemant was collected to determine the concentration of IFN-γ by ELISA. The proliferation of NK cells to sMICA was detected by MTS/PMS. NK cells were labeled with annexin V and PI to analyze their apoptosis. RESULTS: Soluble MICA inhibited the cytotoxicity of NK cells and down-regulated the secretion of IFN-γ, but it showed no effects on the proliferation and apoptosis of freshly isolated peripheral NK cells. CONCLUSION: The soluble MICA shedding from tumor cells could be a pathway of cancer immune evasion by down-regulating the biologic activities of NK cells.