Merkel P A, Chang Y, Pierangeli S S, Harris E N, Polisson R P
Medical Practice Evaluation Center, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
J Rheumatol. 1999 Mar;26(3):591-6.
Antiphospholipid (aPL) antibodies are present in patients with systemic lupus erythematosus (SLE) and/or antiphospholipid antibody syndrome (APS) and are associated with recurrent thromboses, thrombocytopenia, and pregnancy losses. The presence of aPL antibodies is routinely tested using a standardized ELISA that utilizes cardiolipin as antigen (aCL ELISA). This test, although sensitive, is frequently positive in patients with nonrelated autoimmune disorders and some infectious diseases, making the test less specific. Thus there is a need for more specific tests for aCL with equivalent sensitivity to the standard assay. We evaluated the diagnostic utility of a new aPL antibody test kit with a unique phospholipid mixture designed to be more specific than the standard anticardiolipin ELISA.
aPL antibodies (IgG, IgM) were measured by both a standard ELISA and a new ELISA kit (APhL ELISA Kit, Louisville APL Diagnostics, Inc., Louisville, KY, USA) in the baseline serum from patients enrolled in a 5 year inception cohort, prospective study of early rheumatoid diseases: rheumatoid arthritis (N = 70), SLE (70), scleroderma (45), inflammatory myositis (36), and early undifferentiated connective tissue disease (CTD) (165). Diagnosis was based on standardized criteria and determined at the last study visit. A nested group of patients with Sjogren's syndrome (44) was also defined. Serum from 200 blood donors (BD) served as controls. Patients with known APS (33) and antinuclear cytoplasmic antibody positive renal vasculitis (52) were also studied. Laboratory personnel were blinded to sample diagnostic group.
The kit was 90.9% sensitive for detecting APS. Seven patients missed by the kit all had standard aCL values < 40 PL units. Assuming controls do not have APS, the kit was 99.5% specific vs 96.0% for the standard assay. For the patients with CTD, the kit never detected a patient that was not also detected by the standard aCL assay.
The APhL ELISA Kit appears to be more specific than the standard aCL ELISA without adding potential false positive results. The new test may be useful for followup study for patients found to be aCL positive by standard assays to increase specificity for aCL screening.
抗磷脂（aPL）抗体存在于系统性红斑狼疮（SLE）和/或抗磷脂抗体综合征（APS）患者中，与复发性血栓形成、血小板减少症和妊娠丢失相关。aPL抗体的存在通常使用以心磷脂作为抗原的标准化酶联免疫吸附测定（ELISA）来检测（aCL ELISA）。该检测虽然灵敏，但在患有非相关自身免疫性疾病和一些感染性疾病的患者中经常呈阳性，导致该检测特异性较低。因此，需要一种对aCL具有与标准检测相当灵敏度的更特异的检测方法。我们评估了一种新型aPL抗体检测试剂盒的诊断效用，该试剂盒采用独特的磷脂混合物，设计得比标准抗心磷脂ELISA更具特异性。
在一项为期5年的起始队列前瞻性早期类风湿疾病研究中，对入选患者的基线血清进行检测，通过标准ELISA和新型ELISA试剂盒（APhL ELISA试剂盒，美国肯塔基州路易斯维尔市Louisville APL Diagnostics公司）检测aPL抗体（IgG、IgM），这些患者包括类风湿关节炎（N = 70）、SLE（70）、硬皮病（45）、炎性肌炎（36）和早期未分化结缔组织病（CTD）（165）。诊断基于标准化标准，并在最后一次研究访视时确定。还定义了一组干燥综合征患者（44）。200名献血者（BD）的血清用作对照。对已知患有APS的患者（33）和抗核细胞质抗体阳性的肾血管炎患者（52）也进行了研究。实验室人员对样本诊断组不知情。
该试剂盒检测APS的灵敏度为90.9%。试剂盒漏检的7例患者所有标准aCL值均<40磷脂单位。假设对照患者无APS，该试剂盒的特异性为99.5%，而标准检测为96.0%。对于CTD患者，该试剂盒从未检测到标准aCL检测未检测到的患者。
APhL ELISA试剂盒似乎比标准aCL ELISA更具特异性，且不会增加潜在的假阳性结果。这种新检测方法可能有助于对通过标准检测发现aCL呈阳性的患者进行随访研究，以提高aCL筛查的特异性。
