Baldo-Enzi G, Baiocchi M, Crepaldi G
Institute of Internal Medicine, Policlinico Via Giustiniani 2, Padova, Italy.
Clin Chim Acta. 1993 Sep 17;218(1):83-95. doi: 10.1016/0009-8981(93)90224-r.
We compared five immunoassays for lipoprotein(a) (Lp(a)) determination (end-point immunonephelometry, two-site IRMA and three different ELISA methods) in order to verify their agreement. Since it has been demonstrated that human apo(a) structure is closely similar to that of plasminogen, cross-reactivity of apo(a) antibodies with plasminogen represents an important technical problem in serum Lp(a) quantification. On this account we used a plasminogen-free fraction obtained by one-step ultracentrifugation at a density of 1.125 g/ml, in which no plasminogen activity was found. A satisfactory correlation between serum and plasminogen-free fraction Lp(a) values was found for all the methods; the limits of agreement were too high, however, to use serum and fraction interchangeably. Furthermore, it emerged that the different assays were more comparable and individual Lp(a) differences between methods were less spread when plasminogen-free fraction was used instead of serum.
我们比较了五种用于脂蛋白(a)（Lp(a)）测定的免疫测定方法（终点免疫比浊法、双位点免疫放射分析法和三种不同的酶联免疫吸附测定法），以验证它们之间的一致性。由于已经证明人类载脂蛋白(a)的结构与纤溶酶原的结构非常相似，载脂蛋白(a)抗体与纤溶酶原的交叉反应性是血清Lp(a)定量中的一个重要技术问题。因此，我们使用了通过在密度为1.125 g/ml下进行一步超速离心获得的无纤溶酶原部分，其中未发现纤溶酶原活性。所有方法的血清和无纤溶酶原部分的Lp(a)值之间均发现了令人满意的相关性；然而，一致性界限过高，无法互换使用血清和部分。此外，结果表明，当使用无纤溶酶原部分而非血清时，不同测定方法之间更具可比性，方法之间个体Lp(a)差异的分布也更小。
