Annexin V is a human cell protein. More than a hundred proteins that belong to the group of annexins have already been described. Among the most important signs of annexin V is its clear anticoagulant activity. It is found in smooth muscles, many human cells, myocardium, however, the largest amounts are located in the vascular endothelial cells and the placenta. Detection of antibodies to the annexin of the IgG class indicates a chronic pathogenic process that mates with APS, the determination of elevated IgM values indicates an acute process or an exacerbation of the chronic.
Description of these proteins
Annexins are a group of proteins whose distinctive feature is the ability to bind phospholipids to each other. These proteins are needed for signal transmission, organelle transport, cell growth and division, apoptosis. Currently, twelve annexins are known, which differ in their biochemical structure. Normally, annexin V is found in the trophoblastic syncytial layer and vascular endothelium. They are responsible for the active binding of phosphatidylserine molecules that are needed for the blood coagulation process, and thus become a natural anticoagulant.
If antibodies to annexin V appear in the blood, this violates the defense mechanism, which clinically manifests a tendency to the formation of thrombosis. AAnnV can be detected in many diseases characterized by a tendency to form blood clots: systemic scleroderma, systemic lupus erythematosus, habitual miscarriage, but these antibodies are most important in the diagnosis of antiphospholipid syndrome.
APS or antiphospholipid syndrome
APS, or antiphospholipid syndrome, is a clinical-laboratory syndrome characterized by arterial or venous thrombosis, persistent miscarriages and the presence of antiphospholipid antibodies in the blood. It is now known that for antiphospholipid antibodies, antigens are not phospholipids, but plasma proteins associated with them. Among these antigens is annexin V. Two types of AAnnV immunoglobulins are distinguished: IgM and IgG. Antibodies to annexin IgG are believed to be especially characteristic of true (autoimmune, primary) APS. I must say that the search for AAnnV is not a necessary criterion for the diagnosis of APS, but it can be useful in a number of clinical cases.
Testing - why is it required?
A study on antibodies to annexin is used to evaluate prognosis in patients with a positive persistent result of the analysis of the lupus anticoagulant or a high persistent titer of antibodies to cardiolipin. It was established that the detection of AAnnV in this group of people is due to a four-fold risk of spontaneous miscarriage and the same risk of blood clots. The most significant clinical associations have been identified for AAnnV, which are related to immunoglobulins G. The presence of antibodies to annexin V does not appear to be an independent risk factor for such complications. An isolated increase in AAnnV, therefore, in the absence of other clinical and laboratory symptoms of APS, is not used to assess prognosis or diagnosis.
In addition to antibodies to annexin IgM, a laboratory examination with a suspected APS also includes some laboratory tests, so the doctor receives the most complete information about the person. So, for example, the detection of a number of antiphospholipid antibodies (antibodies to beta-2-glycoprotein, antibodies to cardiolipin and AAnnV) in a patient with LA is associated with an eight-fold increase in the probability of spontaneous miscarriage. Other factors that have prothrombogenic potential include deficiency of S and C proteins, antibodies to prothrombin, nephrotic syndrome and arterial hypertension.
A study on antibodies to annexin should be carried out when examining a person with systemic scleroderma. The high AAnnV value in this clinical situation is due to the increased likelihood of developing ischemic skin ulcers of the hands.
Antiphospholipid antibodies may be higher for certain infectious diseases (malaria, HIV infection, viral hepatitis), malignant neoplasms, and drug use (chlorpromazine, procainamide), so the result of the study should be evaluated based on additional instrumental, laboratory, and clinical information.
For research, biomaterial such as venous blood is taken. For proper preparation for the analysis, you can not smoke for thirty minutes before it is surrendered.
The purpose of this study
The study is conducted with the aim of:
- assessing the likelihood of spontaneous miscarriage and thrombosis in people with a positive persistent test result for the lupus anticoagulant and / or a high persistent value of antibodies to cardiolipin;
- assessing the likelihood of severity and development of ischemic ulcers of the hands in patients with systemic scleroderma.
Find out at what time the analysis is scheduled.
Study appointment time
Research is recommended for:
- positive persistent result of the analysis for the lupus anticoagulant and / or high persistent value of antibodies to cardiolipin;
- diagnosing a person with systemic scleroderma.
Next, we consider how the decryption is carried out.
Decoding of this study
Reference indications in the analysis (norm): from 0 to 8 U / ml.
The value of a positive result:
- a high probability of miscarriage and thrombosis, if there are additional symptoms of antiphospholipid syndrome;
- other causes: oncological, infectious diseases, drug use (chlorpromazine, procainamide).
A negative result indicates either the norm or the incorrect taking of biomaterial for analysis.
What can distort the result?
The value of antiphospholipid antibodies can be increased in certain infectious diseases (malaria, HIV infection, viral hepatitis), malignant neoplasms, as well as with the use of drugs (chlorpromazine, procainamide).
In what cases are antibodies to annexin elevated?
Higher values in analysis results
Some publications say that an increase in the concentration of annexin may indicate a violation of the inner walls of the vessels, microcirculation defects that reflect the initial stages of atherosclerosis. At the same time, the increased values of antibodies to annexin with defects in immunity reactions alter the characteristics of the protection of the anticoagulant system, accompanied by the appearance of blood clots and arterial or venous thrombosis. Forming antibodies that bind to phospholipids in the antiphospholipid syndrome bind to annexin, due to which the vascular protective layer degrades and provokes an increase in the likelihood of blood clots.
In the process of interpreting laboratory information, it should be borne in mind that antibodies can transiently appear in the blood with a number of infectious diseases (HIV), taking medications with procainamide, quinidine, phenytoin, as well as with cancer pathologies. The search for antibodies is not included in the criteria for the diagnosis of APS, however, it is useful in laboratory diagnosis if clinical symptoms of antiphospholipid syndrome appear.