[Effects of recombinant soluble MICA protein on the biologic activities of NK cells].

ABSTRACT

AIM: To study the effects of recombinant soluble MHC class I chain-related protein A (sMICA) on the cytotoxicity, secretion of IFN-gamma, proliferation and apoptosis of peripheral NK cells. METHODS: After NK cells were co-cultured with recombinant soluble MICA proteins overnight, the cytotoxicity of NK cell on target cells was detected by flow cytometry. The supernant was collected to determine the concentration of IFN-gamma 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-gamma, 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.