Effects of ionizing radiation on the pattern recognition receptors.

树突状细胞(DC)在免疫系统中发挥着重要作用。本研究调查了暴露于电离辐射下的单核细胞来源的DC是否能对病原体衍生成分和致炎细胞因子产生足够的反应。从黄褐色大衣中分离出的人单核细胞经X射线照射后分化为DC。用脂多糖(LPS)或促炎细胞因子混合物(Mix)刺激DC。未照射和X射线照射的单核细胞经内毒素和混合刺激后的DC经表面抗原表达证实为成熟。然而，在内毒素刺激下，经X射线照射的单核细胞表面CD80和CD83的表达水平低于未经照射的单核细胞DC。在混合刺激下没有观察到这样的减少。类似地，在经X-射线照射的单核细胞中，在内毒素刺激的DC中观察到基质金属蛋白酶-9和细胞因子产生的损害，而在混合刺激下没有观察到这些损害。尽管成熟刺激的类型不同，但照射组的DC刺激T细胞的能力低于未照射组。因此，本研究结果提示，X射线照射对DC成熟的影响取决于所使用的成熟刺激的类型，并且X射线照射尤其削弱DC对内毒素的反应。

Dendritic cells (DCs) play an essential role in the immune system. This study investigated whether DCs from monocytes exposed to ionizing radiation can adequately respond to pathogen-derived components and proinflammatory cytokines. Human monocytes separated from buffy coats were exposed to x-rays and were then differentiated into DCs. DCs were stimulated by lipopolysaccharide (LPS) or proinflammatory cytokine mixture (MIX). The DCs from nonirradiated and X-irradiated monocytes showed maturation after LPS and MIX stimulation as confirmed by findings of surface antigen expression. Upon LPS stimulation, however, the expression levels of CD80 and CD83 on the DCs from the X-irradiated monocytes were lower than those of the DCs from the nonirradiated monocytes. Such reductions were not observed upon MIX stimulation. Similarly, an impairment of matrix metalloproteinase-9 and cytokine production was observed in the LPS-stimulated DCs from the X-irradiated monocytes, whereas these impairments were not observed upon MIX stimulation. The ability of DCs to stimulate T cells was lower in the irradiated group compared with the nonirradiated group despite the type of maturation stimulus. Thus, the present results suggest that the influence of X-irradiation on the maturation of DCs depends on the type of maturation stimulus used and that X-irradiation especially impairs the response of DCs to LPS.