乳腺癌患者可溶性MICA对自然杀伤细胞受体的影响

目的观察乳腺癌患者外周血自然杀伤（NK）细胞杀伤活性及受体的变化，探讨可溶性MICA（sMICA）对NK细胞受体及杀伤活性的影响。方法ELISA法检测外周血血清sMICA的含量。流式细胞术（FCM）检测NK细胞百分比、NK细胞活化性受体NKG2D、抑制性受体KIR（CD158b）表达。MTT法检测NK细胞对乳腺癌细胞株MCF-7的杀伤活性。结果与健康人比较，乳腺癌患者中81．6％表达sMICA，含量为（205．36±71．27）ng／L，且sMICA含量与TNM分期呈正相关。乳腺癌患者外周血NK细胞所占百分比无明显差异，但血清sMICA阳性的乳腺癌患者中NK细胞杀伤活性明显降低，NKG2D表达下降，CD158b表达增高。当NK细胞培养体系中加入sMICA阳性的乳腺癌血清时，其杀瘤活性明显降低【（76．2±6．7）％与（48．4±4．1）％】，NKG2D的表达明显下调[（92．5±7．1）％与（62．5±6．4）％]，而CD158b的表达明显上升【（10．6±3．2）％与（43．6±3．4）％】。sMICA阳性的乳腺癌患者NK细胞与细胞因子IL-15共培养，NK细胞的杀瘤活性、NKG2D的表达明显升高，KIR（CD158b）的表达明显下降。结论乳腺癌外周血血清中sMICA可通过下调NK细胞NKG2D表达以及上调KIR表达，降低NK细胞杀瘤活性。IL-15可逆转sMICA对NK细胞的免疫下调作用。

Effects of sMICA on receptors of NK cells in breast cancer

Objective To observe the expression of cytotoxicity and receptors on NK cells in breast cancer,and investigate the impact of soluble MICA(sohble MHC class Ⅰ-related molecules A,sMICA) on NK cells receptors expression and cytotoxicity.Methods ELISA was used to examine the sMICA in peripheral blood.The expressions of activated receptor(NKG2D),killer inhibitory receptor (KIR)(CD158b) and NK cells were identified by flow cytometry(FCM).Cytotoxicity of NK cells to breast cancer were tested by MTT.Results sMICA was (205.36±71.27)ng/L in breast cancer patients and 81.6 % samples were detected.There were positive correlations between sMICA levels with breast cancer stages.There were no difference of NK cells percentage between breast cancer and healthy person.The cytotoxicity of NK cells and expressions of NKG2D were obviously lower in breast cancer with sMICA(+) than in healthy person,but CD158b was higher in healthy person.After cultured with sMICA,NK cells cytotoxicity decreased from(76.2±6.7)% to(48.4±4.1)% and the expression of NKG2D reduced from(92.5±7.1)% to (62.5±6.4)%,but the the expression of CD158b increased from(10.6±3.2)% to (43.6±3.4)%.IL-15 up regulated the expression of NKG2D and NK cells cytotoxicity,but decreased the expression of CD158b by co-culturation with IL-15 and sMICA in sMICA+ patients with breast cancer.Conclusion sMICA reduced the expression of NKG2D and increased the expression of Kill,which lead to the down regulation of NK cells cytotoxicity.IL-15 can reverse this effect.