Department of Nephrology, Haematology and Immunology, Medical Centre Alkmaar, Alkmaar, The Netherlands.
Blood Purif. 2009;28(3):253-9. doi: 10.1159/000232933. Epub 2009 Aug 14.
Although platelet (PLT) activation and degranulation are well-known phenomena during hemodialysis (HD), controversies still exist about their nature and origin.
PLT characteristics [PLT numbers, mean PLT volume (MPV), PLT distribution width (PDW), PLT large cell ratio (p-LCR), immature PLT fraction] and activation status [CD62p expression, platelet factor 4 (PF4) and beta-thromboglobulin (BTG) plasma levels] were estimated in 19 patients before and during HD. Blood was sampled from both the afferent and efferent lines. Additionally, the influence of low-molecular-weight heparin (LMWH) on PF4 and BTG concentrations was analyzed.
CD62p expression increased in the extracorporeal circuit (ECC) in the first 30 min. Simultaneously, PLT numbers dropped markedly within the ECC. MPV, PDW and p-LCR decreased over time. Like CD62p expression, BTG reached peak values at t30, was exclusively released within the ECC and was not influenced by the application of LMWH. In contrast, PF4 was significantly released outside the ECC in response to LMWH.
PLTs are predominantly activated within the ECC and not on a remote distance. PLTs stick to the ECC, particularly after first passage. BTG is an appropriate marker for HD-induced PLT degranulation, whereas PF4 originates from both activated PLTs and LMWH-induced detachment from the endothelium. PLTs are not exhausted due to the repetitive stimulation of clinical HD. Hence, dialysis modalities with longer duration or greater frequency may be associated with a less beneficial PLT activation profile, which may counteract their clinical benefits.
虽然血小板（PLT）活化和脱颗粒是血液透析（HD）中众所周知的现象，但关于其性质和来源仍存在争议。
在 19 例患者进行 HD 前后，评估了血小板特征[血小板计数、平均血小板体积（MPV）、血小板分布宽度（PDW）、血小板大细胞比（p-LCR）、未成熟血小板分数]和活化状态[CD62p 表达、血小板因子 4（PF4）和β-血栓球蛋白（BTG）血浆水平]。从流入和流出线采集血液。此外，还分析了低分子肝素（LMWH）对 PF4 和 BTG 浓度的影响。
CD62p 表达在体外循环（ECC）的前 30 分钟内增加。同时，ECC 内血小板计数明显下降。MPV、PDW 和 p-LCR 随时间推移而降低。与 CD62p 表达一样，BTG 在 t30 时达到峰值，仅在 ECC 内释放，不受 LMWH 应用的影响。相反，PF4 在外周血中显著释放，对 LMWH 有反应。
PLT 主要在 ECC 内活化，而不在远处。PLT 黏附在 ECC 上，尤其是在第一次通过后。BTG 是 HD 诱导的 PLT 脱颗粒的合适标志物，而 PF4 来源于活化的 PLT 和 LMWH 诱导的内皮细胞脱离。由于临床 HD 的重复刺激，PLT 并未耗尽。因此，持续时间更长或频率更高的透析方式可能与不太有利的 PLT 活化谱相关，这可能会抵消其临床益处。
