REAADS Anti-Cardiolipin (aCL) IgM is an ELISA for the determination of immunoglobulin M anti-cardiolipin antibodies in human serum of plasma in subjects with system lupus erythematosus (SLE), lupus-like disorders (anti-phospholipid syndrome) and other auto-immune diseases. Anti-cardiolipin antibodies are associated with arterial and venous thrombosis, thrombocytopenia and recurrent fetal loss. Presented in automation friendly format (30’ – 30’ – 30’).

  1. Add 100µl of calibrator, controls and samples to microwells
  2. Incubate at room temperature for 15 minutes
  3. Decant contents
  4. Wash 5 times with PBS
  5. Add 100µl of conjugate to each well except the water blank
  6. Incubate at room temperature for 15 minutes
  7. Decant contents
  8. Wash 5 times
  9. Add 100µl of substrate to each well except the water blank
  10. Incubate at room temperature for 10 minutes
  11. Add 100µl of stop solution to each well except the water blank
  12. Add 200µl of distilled or deionized water to the water blank well
  13. Read the O.D of each well at 450nm against a 650nm reference filter (if available) within 30 minutes
What is the clinical significance when samples test positive for the anti-cardiolipin antibodies and are negative for anti-b2GPI?
The aCL assay can detect antibodies of differing specificities. This includes antibodies specific for the cardiolipin molecule itself, and antibodies that are directed against either a cofactor molecule such as b2GPI, or a special binding site created by the interaction of a cofactor with CL. Antibodies directed against CL may be associated with infectious disease, or may be specific for a different cofactor, such as prothrombin. The clinical significance of these antibodies must be assessed in conjunction with the patient’s symptoms, clinical history, and other laboratory findings. Follow-up testing of these patients is recommended in 3-6 months to confirm reactivity. Only b2GPI cofactor dependent antibodies react in the anti-b2GPI assay; these antibodies show a higher correlation with thrombosis and are more specific for the antiphospholipid syndrome.
What are some features of the REAADS anti-Cardiolipin test? The b2GPI test?
The REAADS anti-Cardiolipin test kit and the b2GPI kit are reagent-complete kits. The anti-cardiolipin kit features specific determination of IgG, IgM, and IgA aCL antibodies. The kits are convenient, cost-effective ELISA procedures which give objective, accurate, and reproducible results with short incubations at room temperature.
How does a syphilis infection affect the REAADS anti-cardiolipin test?
Patients with current or prior syphilis infections may have a positive result without increased risk of thrombosis. Anti-cardiolipin antibodies can appear transiently at low levels during many infections. If a patient first tests positive while there are clinical signs of infection, the test should be repeated after an interval of six months.
Summarize the IgG/IgM and IgA REAADS anti-cardiolipin test. What is the normal range?
The test is an indirect ELISA. Diluted serum samples, calibrator sera, and controls are incubated in cardiolipin coated microwells, allowing aCL antibodies present in the samples to react with the immobilized antigen. After their removal of unbound serum proteins by washing, antibodies specific for human IgG, IgM, or IgA labeled with HRP are added forming complexes with the CL bound antibodies. Following another washing step, the bound enzyme-antibody conjugate is assayed by the addition of TMB and H2O2 as the chromogenic substrate. Color develops in the wells at an intensity proportional to the serum concentration of aCL antibodies. The OD is read at 450 nm.

Normal ranges are less than 23 GPL (IgG per liter), less than 11 MPL (IgM per liter), and 22 APL (IgA per liter).