A protocol for determination of anticardiolipin antibodies by ELISA

The anticardiolipin (aCL) test has been widely used by physicians since the mid-1980s for diagnosing patients with antiphospholipid syndrome (APS). Establishment of this diagnosis has enabled effective management of patients with recurrent thrombosis or recurrent pregnancy losses. The test was first established in 1983 as a radioimmunoassay and soon thereafter converted into ELISA. There have been numerous efforts to standardize the aCL test, but precise reproducible measurement of aCL levels is difficult and the use of semiquantitative measurements (high, medium and low) is recommended as this is probably sufficient for clinical diagnosis. Using validated ELISAs for measuring aCL Abs offers greater reproducibility, would reduce interlaboratory variations and limit discrepancies in results between different laboratories. This article details a procedure that takes ∼2 h and summarizes the information available on the aCL ELISA test.