Specimen Information

Type

Gold, SST

Volume

1.0 ml

Transport Info

Centrifuge and immediately transfer serum to separate plastic tube
Refrigerated

Fasting Required?

False

Clinical Significance

To detect potential coagulation problems.

Anticardiolipin antibodies are a heterogeneous group of antibodies that react with negatively charged phospholipids. One subgroup of autoantibodies directed against cardiolipin is frequently found in systemic lupus erythematosus (SLE) patients, as well as in patients with both venous and arterial thrombosis, thrombocytopenia, and recurrent fetal loss. Patients who present with these latter manifestations have what is termed the "antiphospholipid antibody syndrome" (APS). Another subgroup of anticardiolipin antibodies is found in patients with syphilis and other infectious diseases who show no evidence of coagulation disorders.Studies in the early 1990s identified Beta-2 glycoprotein 1 (ß2GP1), or apolipoprotein H, as a necessary cofactor for antiphospholipid antibody binding in immunoassays. ß2GP1 is a 50 kd plasma protein identified as one of the cofactor molecules required for the optimal binding of antiphospholipid antibodies to negatively-charged phospholipids. More recent studies, however, have individually reported that anticardiolipin antibodies derived from autoimmune patients (SLE and APS) were directed against the ß2GP1 molecule alone when coated on polystyrene plates. Other studies have shown conclusively that ß2GP1 is indeed the antigen that antibodies from APS patients are actually binding to, and that the phospholipid merely serves to link the ß2GP1 to the solid phase. These studies also provided evidence that a high density negative charge is necessary to induce a structural change in the native ß2GP1 molecule to render it immunogenic. This structural change can be induced by ß2GP1 binding to the phosphate head region of phospholipid or to an irradiated or chemically treated polystyrene microwell surface.There is a well known potential for traditional anticardiolipin tests to produce false positive results due to cross-reactivity of phospholipid antibodies present in certain infectious disease samples, most notably syphilis, and with certain other autoantibodies such as ones to double stranded DNA. By eliminating phospholipid from the solid phase and using only ß2GP1, the test becomes more specific for detecting potential coagulation problems. Therefore, the ß2GP1 autoantibody test is a more useful and specific assay. It is to be used in conjunction with the traditional anticardiolipin antibody and lupus anticoagulant tests for assessing the risk of thrombosis and fetal loss.