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目的:观察结直肠癌患者NKG2D及其配体MICA/B的表达,研究自然杀伤细胞免疫状态及肿瘤逃避免疫监视的机制。方法:流式细胞术检测40例结直肠癌患者及30例健康体检者外周血自然杀伤细胞绝对计数,NKG2D及其配体MICA/B的表达。ELISA检测血清可溶性MICA的浓度。结果:结直肠癌患者自然杀伤细胞绝对计数、NKG2D、MICA/B的表达均降低,可溶性MICA浓度增高,与对照组比较差异有统计学意义。NKG2D的表达与结直肠癌组织分化程度呈负相关(P<0.01),与病理分期无关(P>0.05);血清可溶性MICA浓度与结直肠癌的病理分期呈正相关(P<0.01),与组织分化程度无关(P>0.05)。结论:结直肠癌患者血清高水平的可溶性MICA,抑制了NKG2D介导的抗肿瘤免疫,可能是肿瘤逃避免疫监视的机制之一。外周血NKG2D的表达与血清可溶性MICA浓度可以作为判断上皮类肿瘤恶性程度的指标。
OBJECTIVE: To observe the expression of NKG2D and its ligand MICA / B in patients with colorectal cancer and to study the immune status of natural killer cells and the mechanism of tumor escape immune surveillance. Methods: The absolute counts of natural killer cells, the expression of NKG2D and its ligand MICA / B were detected by flow cytometry in 40 patients with colorectal cancer and 30 healthy controls. ELISA to detect serum soluble MICA concentration. Results: The absolute counts of natural killer cells, the expression of NKG2D and MICA / B in colorectal cancer patients were all decreased, and the concentration of soluble MICA was increased. There was significant difference compared with the control group. The expression of NKG2D was negatively correlated with the degree of differentiation of colorectal cancer (P <0.01), but not with the pathological stage (P> 0.05). The concentration of serum soluble MICA was positively correlated with the pathological stage of colorectal cancer (P <0.01) The degree of differentiation had no relation (P> 0.05). Conclusion: High levels of soluble MICA in colorectal cancer patients inhibit NKG2D-mediated anti-tumor immunity and may be one of the mechanisms of tumor escape immune surveillance. The expression of NKG2D in peripheral blood and the concentration of serum soluble MICA can be used as indexes to judge the malignant degree of epithelial tumor.