Lin M H, Liao C P, Lee J S, Chin Y W, Hsu C C, Wei J S
School of Medical Technology, Chang Gung University, Kweisan, Taiwan, R.O.C.
Proc Natl Sci Counc Repub China B. 1998 Jul;22(3):129-35.
Digitalis-like immunoreactive factors (DLIF) are special types of steroids with lactone rings in their structures. Clinically, this type of compound can be used as medicine for heart failure; thus, the elevated endogenous DLIF found under certain pathological conditions are interferent substances in digoxin immunoassay. Endogenous DLIF with biological and immunological properties similar to cardiotonic drugs, such as digoxin, have been found in several tissues and body fluids of animals and humans. Since these endogenous Na+, K(+)-ATPase inhibitors can be considered hormones in nature, immunoassays must be selected detection of them to achieve the required sensitivity and specificity. In this study, we used three sets of in-house formulated immunoassays for DLIF and ouabain-like factors (OLF) detection. Using a polyclonal antibody-based ouabain enzyme immunoassay, the mean +/- S.E.M. of OLF in the sera of 10 healthy individuals were determined to be (9.1 +/- 0.9) x 10(-11) M. Using a monoclonal antibody-based ouabain enzyme immunoassay, the mean +/- S.E.M of OLF in the sera of 10 healthy individuals was (8.2 +/- 1.2) x 10(-11) M while using a antibody fragment Fab-based enzyme immunoassay for digoxin, the mean +/- S.E.M of DLIF in 11 healthy individuals was (4.0 +/- 1.2) x 10(-10) M. In conclusion, our immunological data indicate that DLIFs are normal constituents of human blood. Although DLIF is the major component, coexistence of OLF with DLIF in healthy individuals can not be excluded.
洋地黄样免疫反应因子（DLIF）是一类结构中含有内酯环的特殊甾体化合物。临床上，这类化合物可作为治疗心力衰竭的药物；因此，在某些病理条件下发现的内源性DLIF升高是地高辛免疫测定中的干扰物质。在动物和人类的多种组织和体液中都发现了具有与强心苷类药物（如地高辛）相似生物学和免疫学特性的内源性DLIF。由于这些内源性钠钾ATP酶抑制剂本质上可被视为激素，必须选择合适的免疫测定方法来检测它们，以达到所需的灵敏度和特异性。在本研究中，我们使用了三组自行配制的免疫测定方法来检测DLIF和哇巴因样因子（OLF）。使用基于多克隆抗体的哇巴因酶免疫测定法，测定了10名健康个体血清中OLF的平均值±标准误为（9.1±0.9）×10⁻¹¹ M。使用基于单克隆抗体的哇巴因酶免疫测定法，10名健康个体血清中OLF的平均值±标准误为（8.2±1.2）×10⁻¹¹ M，而使用基于抗体片段Fab的地高辛酶免疫测定法，11名健康个体血清中DLIF的平均值±标准误为（4.0±1.2）×10⁻¹⁰ M。总之，我们的免疫学数据表明DLIF是人体血液的正常组成成分。虽然DLIF是主要成分，但不能排除健康个体中OLF与DLIF共存的情况。
