NK细胞活化受体及配体在急性白血病患者外周血中的表达和脱离

Expression and Abscission of Activated Receptors and Their Ligands on/from NK Cells in Peripheral Blood of Patients with Acute Leukemia

本研究旨在从NK细胞活化性受体NKG2D及其相应配体——MICA/B、ULBP-1、2、3的表达和血清中脱离情况来探讨急性白血病患者NK细胞免疫防御功能损伤的可能机制。选择30例初发未治疗的急性白血病患者作为观察对象,10例健康者作为对照,应用流式细胞术检测白血病细胞表面MICA/B,ULBP-1、2、3表达水平,用ELISA法检测血清可溶性MICA、MICB(sMICA,sMICB)及可溶性ULBP1-3(sULBP1-3)水平。结果表明,急性白血病患者NK细胞NKG2D的表达低于正常对照组;急性白血病患者白血病细胞表面不表达或弱表达MICA/B、ULBP1-3;急性白血病患者血清中游离的sMICA和sMICB水平均高于对照组,差异有统计学意义(p<0.01),血清sULBP1-3水平与对照组无明显差异。结论:急性白血病细胞表面MICA和MICB的脱离及ULBP表达缺乏可能是急性白血病细胞发生免疫逃逸的机制之一。

This study was aimed to explore the immune escaping mechanisms based on expression and abscission of human natural killer （NK） cell activating receptors NKG2D and their ligands MICA/B, ULBP-1,2,3 in patients with acute leukemia （AL）. 30 de novo AL patients and 10 healthy persons （control） were enrolled in study. Flow cytometry was used to detect the expression levels of MICA/B, ULBP-1,2,3 on leukemic cells. ELISA was used to detect the levels of soluble MICA （sMICA）, solube MICB （sMICB） and soluble ULBP-1 ,-2,-3 in the serum. The results showed that sMICA, sMICB and ULBP-1 ,-2 ,-3 were not expressed or expressed at very low levels on leukemia cells of the patients; the levels of free sMICA and sMICB in serum of AL patients were higher than that in serum of healthy persons, there was significant difference （p 〈0.01）. But the levels of ULBP 1 -3 in serum of AL patients did not show obvious statistical difference as compared with healthy persons （p 〉 0.05 ）. It is concluded that the negative or low expression of NKG2D ligands （MICA, MICB and ULBPs） on surface of acute leukemia cells may lead to the immune escape of leukemia cells, the abscission of MICA and MICB, and the deficiency of ULBP expression on leukemia cells may be one of immune escape mechanisms of leukemia cells.