Anticardiolipin antibody is "positive", beware of these three situations!

*It is only for medical professionals to read.
Is ACA positive, is it easy to miscarry? Unlike rheumatoid factor, everyone is familiar with it.
When it comes to anticardiolipin antibody (ACA), many people will wonder, what kind of antibody is this? Under what circumstances do I need to test for ACA? What should I do if it is positive? Today we will talk about ACA together.

01 What is an anticardiolipin antibody? First of all, it should be clear that the ACA we mentioned here and the lupus anticoagulant (LA) mentioned last time are all members of the antiphospholipid antibody (aPLs).
They are both a group of phospholipids and/ Or phospholipid binding protein is the autoantibody of the target antigen.

The most common aPLs are LA, ACA, and anti-β2-glycoprotein I (anti-β2-GPI) antibodies.

Cardiolipin is a type of phospholipid, which is widely present in various cells of the body.
It was first discovered in 1906.
At that time, it was only considered as an antigen, and it was named cardiolipin in 1941 [1].

The reason why ACA is valued by people is because of its huge destructive power and pathogenicity.
It can react with a variety of antigenic substances of phospholipid structure, and is often associated with recurrent spontaneous abortion, fetal arrest, and embolism.

ACA is divided into 3 subtypes, namely IgG type, IgA type, IgM type, among these three types, the order of the hazard degree is IgG>IgM>IgA[2].

02 Detection of anti-cardiolipin antibodies my country's 2019 "Expert Consensus on the Clinical Application of Anti-phospholipid Antibody Detection" [3] clearly gives the test specimen requirements and detection methods for anti-phospholipid antibodies.

At present, the ELISA method is routinely used for the detection of ACA.
However, due to the lack of standardization of ELISA and many factors affecting the experimental operation, the chemiluminescence method is gradually being used.
Compared with the ELISA method, the chemiluminescence method has higher sensitivity.
And specificity.

For the different subtypes of ACA, the consensus mentioned that it is recommended to detect ACA-IgG and ACA-IgM antibodies.

In addition, only the serum or plasma antibody titer is greater than 40U or exceeds 99% of the normal population test value can be judged as positive.

03What are the issues to be aware of when anticardiolipin antibodies are positive? ACA is mainly found in patients with autoimmune diseases, such as systemic lupus erythematosus, but it can also occur in patients with malignant tumors (lymphoma, leukemia, lung cancer, etc.
), infectious diseases (syphilis, tuberculosis, etc.
) and even healthy people.

In the case of some drugs (such as chlorpromazine, contraceptives, procainamide, quinidine, phenytoin), ACA may also be positive [3].

Therefore, when interpreting ACA, it is necessary to comprehensively evaluate the patient's clinical symptoms, signs, past history, medication history and other information, and timely communication between clinicians and laboratory departments is necessary when necessary.

1ACA and Thrombosis When talking about ACA, the first thing to talk about is thrombosis.
Thrombosis refers to abnormal blood clotting, which can occur in arteries and veins.

Studies have found that ACA can participate in thrombosis through a variety of mechanisms, such as inhibiting the coagulation cascade catalyzed by phospholipids, inducing monocytes to express tissue factor, reducing fibrinolysis and promoting platelet aggregation.

The serum levels of ACA-IgG and ACA-IgM in patients with recurrent first-onset cerebral infarction were significantly higher than those in healthy controls [4].

It is worth mentioning that although ACA-IgA is not as "pathogenic" as ACA-IgG and ACA-IgM, it seems to be an independent risk factor for thrombosis, and it is also worth evaluating for patients with accidental thrombosis [1].

In the detection of aPLs-related antibodies, the three simultaneous positives of LA, ACA, and anti-β2-GPI antibodies are more likely to form thrombosis than one or two of them [3].

2ACA and bad pregnancy.
Bad pregnancy is often a clinical form of ACA positive.
Common bad pregnancy includes unexplained fetal arrest, recurrent miscarriage, stillbirth, premature delivery and preeclampsia.

ACA can affect the formation of placental syncytiotrophoblasts, promote platelet aggregation to form thrombus, or accelerate placental vasoconstriction, resulting in insufficient blood supply to the fetus and causing fetal death.

Studies have shown that ACA levels in patients with recurrent spontaneous abortions are significantly higher than those in normal delivery, and ACA levels are positively correlated with the occurrence of stillbirth [1].

In addition to the above-mentioned adverse pregnancy, in terms of reproduction, infertility is also related to ACA.
ACA positive can affect embryo implantation and early embryo development.
The mechanism may be related to the effect of ACA on the trophoblast surface phospholipid-dependent antigen causing cell damage.
The rupture of interphospholipid adhesion molecules, which in turn leads to a decrease in the acceptance of the embryo by the uterus.

3ACA and Antiphospholipid Antibody Syndrome (APS) We talked about the many possible situations of ACA positive, so you may ask which department should you look for when ACA is positive? There is no doubt that the rheumatology and immunology department needs to be considered.

The reason for this lies in the ACA and APS to be mentioned.

APS is an autoimmune disease mediated by aPLs, with recurrent thrombosis and miscarriage as the main clinical features.

APS can be divided into primary and secondary clinically.
Many APS are secondary, often secondary to autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and Sjogren’s syndrome.

In addition, a rare type of APS is malignant APS, which is mainly manifested as a large number of thrombosis in a short period of time, involving multiple important organs, which can cause organ failure or even death.

04 Summary In summary, ACA is related to thrombotic events and adverse pregnancy events.
This suggests that clinicians should be alert to the possibility of ACA positive when encountering the following patients, such as arteriovenous thrombosis that cannot be explained by other reasons, and multiple pathological pregnancies ( Recurrent miscarriage, fetal arrest, stillbirth) and younger strokes.

In addition, APS is a disease that is highly related to ACA.
Thrombosis and poor pregnancy are often its clinical manifestations.
When ACA is positive, you should actively consult a specialist to check for rheumatism. Reference materials: [1]Wang Wenqiang, Li Zhongxin, Sun Meng, et al.
Application of anticardiolipin antibodies in clinical diagnosis[J].
Medical Laboratory Science and Clinices, 2020,31(12):33-36.
DOI:10.
3969/ j.
issn.
1673-5013.
2020.
12.
009.
[2] Li Yan, Tan Li.
Check items and indications for antiphospholipid syndrome and its guidance for clinical treatment[J].
China Family Planning and Obstetrics and Gynecology,2020,12 (05):14-18.
[3] National Rheumatism Data Center, Chinese Medical Doctor Association Rheumatology and Immunology Physician Branch Autoantibody Detection Professional Committee, National Immunological Disease Clinical Medicine Research Center.
Expert consensus on the clinical application of antiphospholipid antibody detection[J ].
Chinese Journal of Internal Medicine, 2019,58(7):496-500.
DOI:10.
3760/cma.
j.
issn.
0578?1426.
2019.
07.
003.
[4]Sun Jihong, Zhang Yan, Zhang Xunyue, Fan Ning, Mu Junping, Yun Ping.
Relationship between patients with cerebral infarction and serum anticardiolipin antibodies and β2 glycoprotein I antibodies[J].
Laboratory Medicine and Clinics,2016,13(08):1100-1101.