If you suspect chronic infections, allergies, and autoimmune diseases, doctors prescribe an analysis for circulating immune complexes (CECs). This study allows you to determine the stage of the inflammatory process. Such a test is usually carried out in combination with other immunological tests. What analysis indicators are considered normal? And what causes the increase in the level of the CEC? We will consider these issues in the article.
What it is
When a foreign protein (antigen) enters the body in immune cells, the production of special globulins begins. In this case, circulating immune complexes appear in the blood. They are macromolecular compounds that appear when antibodies interact with antigens.
Normally, these compounds are quickly removed from the body through phagocytes. Also, complexes are destroyed in the liver and spleen. With some pathologies, their elimination from the body slows down. If the concentration of such substances becomes excessively high, then there is a risk of deposition of CEC in the tissues. This can trigger an inflammatory process.
What kind of analysis do you need to pass
How to determine the concentration of circulating immune complexes? To do this, you need to pass a special blood test to the CEC. Such an immunological study is carried out in many clinical laboratories. This test is prescribed for the following purposes:
- for the diagnosis of inflammatory processes developing due to deposition of CEC in the tissues;
- to determine the etiology of allergies;
- to detect autoimmune diseases;
- to monitor the patient's condition with glomerulonephritis and chronic infections;
- to evaluate the effectiveness of the prescribed treatment.
It is important to remember that from the results of this study it is impossible to judge the exact concentration of CEC in the tissues. The test data allow only to assess the degree of activity of the inflammatory process.
Indications
A blood test for circulating immune complexes is prescribed if you suspect the following diseases:
- systemic lupus erythematosus;
- scleroderma;
- joint inflammation;
- polymyositis;
- glomerulonephritis;
- allergies
- serum sickness.
An indication for a test for the CEC is also chronic persistent infection. This is the name of the pathology provoked by the constant presence of viruses, fungi and bacteria in the body.
Test preparation
This analysis is taken in the morning before meals. A few days before the delivery of biomaterial, the following rules must be observed:
- refuse to eat fatty foods;
- do not drink alcohol;
- avoid physical and emotional stress;
- quit smoking 2-3 hours before blood donation.
How is the analysis
Blood is taken from a vein for examination. The biomaterial is placed in a sealed tube and delivered to the laboratory. It is centrifuged and the plasma is separated from the shaped elements.
Plasma is examined by the enzyme immunoassay. A special substance, complement C1q, is added to the test tube with blood serum. This is a protein that interacts with the CEC. After that, the density of the solution is measured using a photometer. Based on these data, the number of circulating immune complexes is calculated. Decryption of the analysis can be obtained on hand approximately 2-4 days after the delivery of the sample.
Norms
As already mentioned, this study does not indicate a concentration of CEC in the tissues. The test results indicate only the level of these compounds in blood plasma. It is also important to remember that different units of CEC measurement are used in laboratories.
The concentration of circulating immune complexes in the norm can be from 0 to 120 RU (relative units) per 1 ml of serum. The CEC indicator can also be measured in arbitrary units (cu). Valid values are from 0.055 to 0.11 cu
In children, the norm of circulating immune complexes is the same as in adults. The reference values for this test are independent of the patient's age.
Reasons for the increase
For what reasons can the CEC be raised? Deviations from the norm in a big way can be noted with various diseases. Such pathologies can be divided into 3 groups:
- allergic reactions;
- autoimmune processes;
- infection penetration.
The first group of diseases is caused by the introduction of foreign antigens into the body. With allergies, CECs are formed in an increased amount. The body does not have time to remove these compounds. Such pathologies include:
- allergic reactions to drugs;
- serum sickness (hypersensitivity to vaccines, serums and blood components);
- allergic inflammation of the alveoli of the lungs (reaction to inhalation of allergens);
- allergy after an insect bite;
- Dühring's herpetiform dermatitis (skin lesions with the formation of a vesicle rash).
Autoimmune processes often cause an increase in CEC. In rheumatic diseases, immune complexes are deposited in the tissues and cause inflammation. This is noted with the following pathologies:
- systemic lupus erythematosus;
- scleroderma;
- glomerulonephritis (lupus genesis);
- rheumatoid arthritis;
- periarteritis nodosa;
- Crohn's disease;
- Sjogren's syndrome;
- systemic vasculitis;
- autoimmune inflammation of the thyroid gland.
In addition, bacterial, viral and fungal infections can become the cause of increased CEC. When the pathogen enters the body, a large number of antigen-antibody complexes are formed. They are not always completely eliminated from the body and accumulate in plasma. Also, the cause of high levels of CEC are malignant tumors and parasitic pathologies.
Increased immune complexes are noted in patients undergoing organ transplants. In this case, this does not indicate an unfavorable prognosis of the disease.
Performance decline
If during the initial analysis the patient has lowered circulating immune complexes, this does not mean pathology. The CEC indicator may even be zero. This value is a variant of the norm.
If the patient has had a high level of CEC in the past, then a decrease in the indicator is a favorable sign. This suggests that the therapy has yielded positive results.
Additional research
With deviations in the CEC, the patient is prescribed an immunogram. This is an extended blood test, which shows the state of the body's defenses. Often, a CEC analysis is performed as part of this test.
One of the most important indicators of this test is the activity of phagocytosis. It is thanks to the activity of phagocytic cells that the circulating immune complexes are eliminated from the body. The norm (in percent) of phagocytosis activity is considered indicators from 65 to 95%.
The more the phagocytosis activity is reduced in a patient, the more CEC accumulates in the tissues. In addition, when conducting an immunogram, the number of lymphocytes, immunoglobulins, markers of macrophages and monocytes is estimated, and the leukocyte formula is determined. Such a comprehensive study allows you to obtain detailed data on the state of the immune system.
The results of the immunogram must be shown to the attending physician (rheumatologist, infectious disease specialist, allergist, immunologist). Depending on the proposed diagnosis, the patient will be prescribed appropriate treatment.