尿毒症病人循环单核细胞Fas的表达及血浆FasL水平

Expression of Fas on monocytes and the level of plasma soluble FasL in patients with chronic renal failure

目的 慢性肾功能衰竭 (肾衰 )病人单核细胞功能低下与其凋亡加速有关 ,兹拟进一步探讨尿毒症病人单核细胞凋亡加速的机制。方法 对 7例尿毒症未透析病人和 18例血液透析 (血透 )病人进行观察 ,以 15例正常人为对照。采用流式细胞仪检测单核细胞Fas和Fas配基 (Fasligand ,FasL)的表达 ;以ELISA法测定血浆中可溶性FasL(sFasL)的水平。在体外将单核细胞与重组人FasL共同孵育 ,抽提DNA后用碘化丙啶染色、流式细胞仪检测单核细胞凋亡率 ,四甲基偶氮唑蓝 (MTT)法观察单核细胞存活率。结果 尿毒症未透析病人和血透病人单核细胞Fas的表达较正常人明显上调(P <0 0 5 ) ;血透病人的Fas表达水平高于非透析病人 (P <0 0 5 ) ,但使用聚砜膜和纤维素膜透析器血透的病人之间以及透析前、后Fas的表达差异无显著性 (P >0 0 5 )。正常人和尿毒症病人的单核细胞表面均未检测出FasL表达。正常人血浆中未能检测出sFasL ,但尿毒症病人血浆中存在有sFasL ;sFasL的水平在尿毒症未透析病人和血透病人之间、血透病人透前与透后之间、以及采用聚砜膜和纤维素膜透析器进行透析的两者之间差异均无显著性 (P >0 0 5 )。单核细胞与重组人FasL在体外共同培养2h后 ,血透病人单核细胞的凋亡率较正常人明显增高 ,而其存活率则较正常?

Objective The dysfunction of monocytes in uremic patients has been demonstrated to be associated with monocyte accelerated apoptosis The study was conducted toelucidate the mechanisms by which monocyte apoptosis was induced Methods seven non dialyzed chronic uremic patients and 18 hemodialysis (HD) patients were enrolled in the study Fifteen healthy volunteers were selected as controls The expression of Fas and Fas ligand (FasL) was examined by immunofluorescent staining and flow cytometer analysis The levels of soluble FasL (sFasL) in plasma were analyzed by enzyme linked immunosorbent assay (ELISA) The percentage of apoptotic cells in monocytes cultured in vitro with recombinant human FasL (rHu FasL) was quantitated by DNA content analysis after extraction of the degraded DNA Monocyte survival rate was analyzed by 5 diphenyl tetrazolium bromide (MTT) staining Results Expression of Fas on monocytes was significantly higher in uremic and HD patients than that in healthy subjects Higher levels of Fas expression were demonstrated on monocytes from HD as patients compared with those from non dialyzed patients There was no difference in monocyte Fas expression between pre and post dialysis session and between patients using polysulfone and cellulose dialyzer There was no detectable FasL expression on monocytes from both uremic patients and healthy controls Plasma sFasL could be detected in uremic and HD patients, but not in healthy controls There was no significant difference in levels of plasma sFasL between non dialyzed and HD patients, pre and post dialysis session, and patients treated with polysulfone and cellulose dialyzer When monocytes were cultured in vitro with rHu FasL for 2 hours, higher levels of apoptosis and lower survival rate were found in monocytes from HD patients as compared with those from healthy controls Conclusion The up regulated expression of functional Fas on monocytes and the presence of sFasL in plasma may contribute to the accelerated apoptosis of monocytes seen in uremic patients