Kobayashi E, Kitano E, Kondo H, Kitamura H
Department of Medical Technology, Osaka Prefectural College of Health Sciences, Habikino.
Rinsho Byori. 1999 Feb;47(2):160-4.
It is generally accepted that complement activation does not proceed in EDTA- and citrate-plasma because of calcium chelation by EDTA and citrate. However, there were several cases with low CH50 level in serum and citrate plasma and normal CH50 level in EDTA plasma, suggesting that complement might be activated in citrate-plasma but not in EDTA-plasma. The present study deals with the inhibitory effect of EDTA and citrate on complement activation. CH50 was assayed in serum or plasma containing various concentrations of EDTA or citrate after incubation with latex particles bearing immunoglobulin. It was revealed that complement activation proceeded in the presence of 2.0 mmol/l of EDTA but was inhibited in the presence of 2.5 mmol/l of EDTA, while blood coagulation was inhibited in plasma containing EDTA higher than 2.0 mmol/l. As to citrate, complement activation proceeded in the presence of 25 mmol/l of citrate but was inhibited in the presence of 50 mmol/l of citrate, while blood coagulation was inhibited in plasma containing citrate higher than 6.2 mmol/l. Thus, it was indicated that, as usual plasma in clinic contains 3.5 mmol/l of EDTA or 10.9 mmol/l of citrate, complement can be activated in citrate-plasma but not in EDTA-plasma. Similar conclusion was obtained by another experiment using ordinary vacuum-type blood collection tube for EDTA-2K plasma, EDTA-2Na plasma and citrate plasma.
一般认为，由于EDTA和柠檬酸盐可螯合钙，补体激活在EDTA血浆和柠檬酸盐血浆中不会发生。然而，有几例血清和柠檬酸盐血浆中CH50水平较低，而EDTA血浆中CH50水平正常，这表明补体可能在柠檬酸盐血浆中被激活，但在EDTA血浆中未被激活。本研究探讨了EDTA和柠檬酸盐对补体激活的抑制作用。在用携带免疫球蛋白的乳胶颗粒孵育后，测定含有不同浓度EDTA或柠檬酸盐的血清或血浆中的CH50。结果显示，在2.0 mmol/l的EDTA存在下补体激活可以进行，但在2.5 mmol/l的EDTA存在下被抑制，而当血浆中EDTA高于2.0 mmol/l时血液凝固被抑制。对于柠檬酸盐，在25 mmol/l的柠檬酸盐存在下补体激活可以进行，但在50 mmol/l的柠檬酸盐存在下被抑制，而当血浆中柠檬酸盐高于6.2 mmol/l时血液凝固被抑制。因此，表明由于临床常用血浆含有3.5 mmol/l的EDTA或10.9 mmol/l的柠檬酸盐，补体可以在柠檬酸盐血浆中被激活，但在EDTA血浆中不能被激活。通过使用普通真空型采血管分别采集EDTA - 2K血浆、EDTA - 2Na血浆和柠檬酸盐血浆进行的另一项实验也得出了类似的结论。
