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Anticardiolipin Antibodies and Lupus

posted in antiphospholipid syndrome on February 7, 2024 by

Gavin Abson

Updated February 21, 2024

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The immune system of many lupus patients produce anticardiolipin antibodies. These antibodies, known for their connection to various autoimmune conditions (especially blood clots and pregnancy complications), often emerge as significant players in lupus patients.

Donald Thomas, MD author of The Lupus Encyclopedia for Gastrointestinal symptoms in lupus blog post

This blog on “Anticardiolipin Antibodies and Lupus” was edited and contributed to by Donald Thomas, MD; author of “The Lupus Encyclopedia.” Parts of this blog post come from “The Lupus Encyclopedia: A Comprehensive Guide for Patients and Health Care Providers, edition 2“

Unraveling the Basics

Anti-cardiolipin antibodies are a family of antibodies that, when present in elevated levels, can have implications for the cardiovascular system. Their association with lupus also stems from their role in provoking a cascade of events contributing to the disease’s complexity.

The Immunological Tango

In lupus, the immune system becomes a double-edged sword. Instead of safeguarding the body, it turns against itself. Anti-cardiolipin antibodies, as part of this immune dysregulation, target cardiolipin. Cardiolipin is a fatty molecule (called a phospholipid). Doctors initially discovered it in animal hearts in the 1940s. “Cardio-” comes from the Greek word for “heart.” The inner mitochondrial membranes of cells contain our cardiolipin. However, cardiolipin is not the only phospholipid against which lupus produces antibodies. Anticardiolipin antibodies are part of a larger family of antibodies called antiphospholipid antibodies.

Clinical Implications in Lupus

Antiphospholipid antibodies (including anti-cardiolipin antibodies) in lupus patients hold clinical significance. Elevated levels are associated with an increased risk of blood clots, leading to conditions such as deep vein thrombosis and pulmonary embolism. This heightened blood clot risk adds extra complexity to managing lupus. When antiphospholipid antibodies cause blood clotting in the placenta, pregnancy problems can occur. These possible complications include miscarriage, stillbirth, low fetus body weight, preeclampsia, and eclampsia.

About 55 percent of people with SLE are positive for anticardiolipin antibodies (ACLA). The percentage varies from 20% to 87%, depending on the study population’s test method. They appear as IgG, IgM, or IgA anticardiolipin antibodies.

The “Other” Antiphospholipid Antibodies

The most important antiphospholipid antibodies that increase the risk of blood clots are ACLA, lupus anticoagulant, and beta-2-glycoprotein-1 antibody. Lupus anticoagulant especially increases the potential for complications during pregnancy, but they all can. The higher the levels of any of these, the greater the risk for blood clots and pregnancy problems. If all three antiphospholipid antibodies occur in someone, we call that “triple positivity.” Patients with triple positivity are at the highest risk for blood clots and pregnancy complications.

Other antiphospholipid antibodies may increase the risk for blood clots, but this has not been proven. They include anti-phosphatidylserine antibodies and antibodies directed toward phosphatidylserine prothrombin complexes. Some patients with APLAs also have a false-positive serologic test for syphilis.

Antiphospholipid antibodies can appear before the diagnosis of lupus

Close to 20% of SLE patients are positive for antiphospholipid antibodies an average of 3 years (up to 7.5 years) before being diagnosed with lupus. These patients tend to have more severe disease with an increased chance for antiphospholipid syndrome (discussed below), lupus nephritis (kidney inflammation), and neuropsychiatric lupus

Beyond Thrombosis: Other Manifestations

While the association with blood clots is noteworthy, antibodies in lupus can have broader implications. They are linked to recurrent pregnancy loss, posing challenges for those wanting to have a successful pregnancy. When someone with blood clots or pregnancy complications has antiphospholipid antibodies, doctors call it antiphospholipid syndrome (APS).

Not all people with antiphospholipid antibodies have APS. Over time, approximately 50% of SLE patients with antiphospholipid antibodies (such as anticardiolipin antibodies) may get blood clots or have pregnancy complications. Higher levels of IgG anticardiolipin antibodies (ACLAs) are especially associated with an increased risk of blood clots. However, they can also occur with elevated IgM and IgA ACLAs. A positive IgM ACLA may also increase the risk of developing hemolytic anemia.

2023 EULAR/ACR antiphospholipid management guidelines add new manifestations

APS can cause numerous other problems other than just blood clots and pregnancy complications. In 2023, the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) approved new guidelines for the management of antiphospholipid syndrome. These guidelines were a major advancement and list many of the other complications of APS to include:

Diagnosis and Monitoring Anti-Cardiolipin Antibodies and Lupus

Detecting anti-cardiolipin antibodies (often abbreviated as ACLA) is a crucial aspect of lupus diagnosis and management. Lupus experts generally recommend checking antiphospholipid antibodies (APLAs) as an important part of diagnosing someone with systemic lupus erythematosus (SLE). APLAs are one of the 2019 EULAR/ACR criteria of the SLE classification crit. Regular monitoring of their levels aids in assessing the patient’s risk for blood clots and pregnancy complications and adapting treatment strategies accordingly.

Treatment Strategies

Managing APLAs in lupus involves a multi-faceted approach. Doctors often prescribe blood thinners (anticoagulation) for APS to reduce the risk of blood clots and pregnancy problems. Doctors often prescribe blood thinners (especially heparin, warfarin, and low-dose aspirin) to help prevent blood clots and pregnancy losses. Hydroxychloroquine (Plaquenil) helps to reduce APLA blood levels and reduces the risk for blood clots.

Navigating the Complexity of Anticardiolipin Antibodies and Lupus

ACLAs and other APLAs add an overall layer of complexity to the intricate tapestry of lupus. Understanding their role is vital for both clinicians and patients. Dr. Thomas strongly feels that all lupus patients should learn about their entire medical situation as this empowers them to proactively take better care of their lupus. Ask your rheumatologist (or other lupus doctors) if you are positive for APLAs, which ones, and also their results. If you have not had all of them measured, tactfully ask your doctor if they could measure them. Lupus experts recommend measuring APLAs within six months of the diagnosis of SLE.

For more in-depth information on anticardiolipin antibodies and lupus:

Read chapters 4 and 9 of The Lupus Encyclopedia, edition 2

Look up your symptoms, conditions, and medications in the Index of The Lupus Encyclopedia

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9 Comments

  1. Was surprised you did not list lupus anticoagulant and antibeta2glycoprotein1 which are by far the most important APLA. (From who is triple positive.)

    • DR: Of course you are correct. This article was only about ACLA and B2GP-1 and LAC will be in another post. However, that is a great idea to at least mention them. I’ll make an addendum and thanks for the advice. It will help patients a lot

      Donald Thomas, MD

  2. How often should the APLAs levels be monitored when they are positive? Is the monitoring frequency affected if you have low platelets or hemolytic anemia? Thank you.

    • Penelope: Interesting question. Dr. Petri at Johns Hopkins showed that they can be negative and be intermittently positive and clinically useful. Therefore, I do repeat them in patients at risk (eg low platelets and AIHA).

      Donald Thomas, MD

  3. I was negative for these antibodies at diagnosis seventeen years ago. Does that mean I will never develop a problem or should I be re-tested at some point? Thank you.

    • Ginger: Dr. Michelle Petri at Johns Hopkins did a study that showed they could initially be negative and then turn up positive and be important. I think that most rheumatologists and lupus experts do not repeat them unless something occurs that looks suspicious (like low platelets, or livedo reticularis, or a blood clot). Since hydroxychloroquine can reduce antibody levels, theoretically, a well-treated patient who was initially negative should stay negative if their lupus is doing well.

      Thanks for your question,

      Donald Thomas, MD

  4. What is the “Coagulation Factor VIII Activity Assay”for? Is it related to Antiphospholipid? Thank you.

    • jyK: Factor VIII activity is used to help diagnose a bleeding disorder called hemophilia A. Its tie with lupus is that if someone has lupus anticoagulant (LAC, one of the antiphospholipid antibodies), LAC can interfere with the test and cause a falsely low factor VIII activity level.

      Donald Thomas, MD

  5. Dear Dr. Thomas,
    I hope this note finds you well. Your expertise and thoughtful approach to an autoimmune disease SLE have not only helped me feel more informed about my health issues but have also provided me immense comfort and reassurance during a challenging time.
    The book that you wrote is an absolute treasure, explaining the conditions, symptoms, pathology results and the treatment options available.
    Thank you once again for your outstanding care and compassion. Please know that your efforts have made a significant difference in my life, and I am sure, in many other lives.
    Olena Luggassi

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