The demonstration of lupus anticoagulant by an enzyme-linked immunoadsorbent assay.

Lupus anticoagulant, an autoantibody associated with thromboembolic disease and pregnancy loss, is currently identified by its capability to prolong phospholipid-dependent coagulation tests, such as the activated partial thromboplastin time (APTT). The use of a coagulation assay for the detection of an antibody has several inherent disadvantages: fresh plasma is required for accurate testing, prolongation of coagulation test(s) is not specific for lupus anticoagulant, and coagulation assays are not easily manipulated for the characterization of antigen-antibody interactions. Using partial thromboplastin an the antigen, we have developed an enzyme-linked immunoadsorbent assay (ELISA) for the detection of lupus anticoagulant. Fifteen women with lupus anticoagulant (being evaluated for recurrent pregnancy loss or autoimmune disease) and 40 lupus anticoagulant-negative controls (including 20 with recurrent pregnancy loss, 12 parous women, and 8 with known autoimmune disease) were evaluated using the APTT and ELISA assays for lupus anticoagulant. All patients with lupus anticoagulant, as defined by the APTT, had significantly elevated IgG (sensitivity and specificity, 100%) or IgG + IgM (sensitivity 93%, specificity 95%) levels compared to controls.