Exner T, Triplett D A, Taberner D A, Howard M A, Harris E N
Haematology Department, Westmead Hospital, Westmead, Sydney, Australia.
Thromb Haemost. 1990 Nov 30;64(3):478-84.
Six lyophilized plasma samples were sent to 20 "expert" laboratories for assessment of lupus anticoagulant (LA). Four samples contained pooled LA of graded potency mixed with aged normal plasma. One contained LA plus cephalin phospholipid and one contained a nonspecific venom anticoagulant. Sixteen methods were used overall with some participants using up to 8 methods. Results were scored in regard to the known potencies of LA in the samples and other known induced defects. Activated partial thromboplastin time (APTT) tests used by most participants for preliminary screening were relatively sensitive, but non-specific. Platelet or phospholipid neutralization procedures (PNP) appeared to be sensitive and specific but showed a non-linear response to increased LA content. Kaolin clotting time (KCT) tests showed the most sensitive response to increased LA content but the weaker LA were not scored as abnormal by most laboratories as the samples may have contained platelet fragments. Other commonly used tests such as the tissue thromboplastin inhibition (TTI) test and the dilute Russell's viper venom test (DRVVT) were carried out somewhat inconsistently. The variability in performance of tests in different laboratories indicates that standardization of methodology is urgently required. Generally it seemed that most clotting tests were "bypassed" by the addition of phospholipid to a known LA-positive sample in apparently direct proportion to their sensitivity. Sample preparation, especially prevention of contamination with activated platelets is a vital preliminary part in the assay of LA.
六个冻干血浆样本被送往20个“专家”实验室，以评估狼疮抗凝物（LA）。四个样本含有不同效价的混合LA与老化的正常血浆。一个样本含有LA加脑磷脂，另一个样本含有非特异性蛇毒抗凝剂。总共使用了16种方法，一些参与者使用了多达8种方法。根据样本中LA的已知效价和其他已知的诱导缺陷对结果进行评分。大多数参与者用于初步筛查的活化部分凝血活酶时间（APTT）试验相对敏感，但不具有特异性。血小板或磷脂中和程序（PNP）似乎敏感且特异，但对LA含量增加呈非线性反应。高岭土凝血时间（KCT）试验对LA含量增加的反应最为敏感，但由于样本可能含有血小板碎片，大多数实验室并未将较弱的LA评为异常。其他常用试验，如组织凝血活酶抑制（TTI）试验和稀释蝰蛇毒时间（DRVVT）试验的操作有些不一致。不同实验室检测性能的差异表明，迫切需要对方法进行标准化。一般来说，在已知LA阳性的样本中添加磷脂后，大多数凝血试验似乎都被“绕过”，这显然与其敏感性成正比。样本制备，尤其是防止被活化血小板污染，是LA检测至关重要的前期步骤。
