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Antibodies to double-stranded DNA - features, norms and decoding

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Antibodies to native DNA are one of a group of antinuclear or antinuclear autoantibodies that are produced by the human immune system when it cannot distinguish between “self” and “non-self” protein compounds.

Target substances are located in the cell nucleus. Antibodies to native DNA specifically target genetic material (DNA) located in the nucleus, causing damage to organs and tissues.

What is it for

The presence of antinuclear antibodies in the blood is directly associated with an autoimmune disorder such as systemic lupus erythematosus, in which they are found in 95% of cases. The test for antibodies to native DNA is quite specific for this condition, however, only in 50-70% of people with lupus, it can be positive. If the patient has positive antinuclear antibodies, the native DNA antibody test can be used to differentiate lupus from other autoimmune disorders that have similar clinical signs and symptoms.

Antibodies to native DNA are often prescribed together with other autoantibodies, such as antibodies to histones, antibodies to phospholipids to make a diagnosis. Specifically, a test for antibodies to native DNA can be used to monitor the severity of the disease in patients already diagnosed with systemic lupus erythematosus, to monitor the complications of this disease, for example, lupus nephritis, which develops when circulating immune complexes (CECs) settle in the kidneys.

Studies on antinuclear antibodies are carried out with the development of the following conditions:

  • muscle pain
  • arthritis,
  • a red rash that often resembles a butterfly in the area of ​​the nose and cheeks,
  • fever,
  • fatigue and weakness
  • photosensitization,
  • weight loss and hair loss,
  • numbness or tingling in the arms or legs,
  • inflammatory diseases of organs and tissues, including kidneys, lungs, heart, central nervous system and blood vessels.

What are antibodies?

The human immune system produces antibodies, the so-called special proteins, which fight against various parasites, viruses, fungi, bacteria, that is, with foreign elements at the genetic level. The task of any antibody is to destroy foreign material and not touch the native cells, which is called the mechanism of self-tolerance.

There are times when the response of the immune system is directed against its own tissues and cells, and not foreign ones. Then there is the development of an autoimmune disease, and antibodies produced against their own cells and their components are called autoimmune by specialists.

If a serious “breakdown” of the immune system occurs, the level of autoantibodies rises, which becomes quite enough for the patient to be diagnosed.

Antibodies to double-stranded DNA is not one antibody, but their whole complex, the target of which is the DNA of the cell nucleus.

The analysis for antibodies is highly sensitive in the diagnosis of SLE, that is, with a positive result, we can talk about confirming the diagnosis. In 70-80% of cases, patients are identified by this analysis. However, due to the insufficient sensitivity of the study, great caution is required when reading the results of the analysis, since if the result is negative, then it is far from the fact that the patient does not have SLE.

These tests are most often prescribed by a rheumatologist. But the direction can be prescribed by a therapist, and a nephrologist, and a dermatologist. Everything will depend on which specialist the patient initially addressed. An immunological laboratory is where antibodies are tested. Special preparation for the analysis is not needed.

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SLE - systemic lupus erythematosus

SLE is a severe autoimmune disease that affects several systems and organs at the same time (the brain, skin, kidneys, joints, blood vessels, and heart systems). The simultaneous presence of symptoms in all organs is not necessary. The manifestations of lupus erythematosus are quite diverse: in one person skin symptoms will prevail, in another, for example, renal.

Antibodies to native double-stranded DNA will help identify this disease.

Risk factors for developing systemic lupus erythematosus

  • Changes in the hormonal background (childbirth, pregnancy, menstruation) that cause prolactin and estrogen, which explains the high frequency, 90%, of diseases, among the female population.
  • A predisposition at the genetic level, which is confirmed by the presence of relatives of patients with SLE with a low level of some HLA system antigens and autoantibodies.
  • Medicines - Methyldopa, Procainamide, Hydralazine.
  • Viral infection that triggers autoimmune processes.
  • Solar radiation (ultraviolet rays cause skin cells to apoptosis, expose DNA, and it becomes visible to the immune system).

Analysis of antibodies to double-stranded DNA is very informative.

Symptoms of SLE

Common signs of manifestation can be called an increase in lymph nodes, fatigue and weakness, fever, weight loss, pain in joints and muscles.

  • Lupus nephritis or kidney damage (kidney function is reduced and there is a triad of laboratory symptoms).
  • Arthralgia and arthritis, which cause inflammation and pain in the joints of the wrists, hands, an X-ray of which will show a decrease in bone density around the joint (periarticular osteoporosis), but there will be no erosion.
  • Serositis, that is, inflammation of the serous membrane of the lungs and heart (pleurisy, pericarditis).
  • Photosensitivity, causing worsening of symptoms after exposure to the sun.
  • Rashes, including on the face, butterfly-like rash. Antibodies to double-stranded DNA will be detected necessarily.
  • Nephritic syndrome - 45-65%.
  • Microhematuria - the presence of 80% of red blood cells in the urine sediment.
  • Proteinuria is associated with a loss of protein together with urine in a volume of more than 0.5 g / s, i.e. 100%.
  • The appearance of a significant number of white blood cells (pyuria) in the urine is very rare, especially in the absence of urinary tract infections.
  • Cotton-like foci form on the retina, and the optic papilla also swells.
  • The presence of acute lupus pneumonitis, lung damage, the association of cough and fever with spotted alveolar infiltrate.
  • Manifestations of neuropsychiatric conditions, ranging from depression to epileptiform paroxysms, psychoses and visual impairments.

    If a patient with SLE is found to have antibodies to double-stranded DNA, repeated monitoring is required after 1-3-6-12 months. It depends on the severity of the disease. In these patients, the risk of developing kidney damage is increased, because anti-DNA complexes with immune complexes lead to kidney damage.

    AntiDNA Assay

    This analysis is necessary:

    • To predict the success of treatment.
    • When a systemic autoimmune disease is suspected.
    • When the result of an ENA antibody, the antinuclear antibody test is positive.
    • When symptoms of SLE are present.
    • When a systemic disease is suspected, especially SLE.
    • For differential diagnosis of articular syndrome.
    • When a positive test result for antinuclear antibodies.
    • To predict the development of kidney damage.
    • To control the flow of hard currency.

    What happens to a person when he has antibodies to double-stranded DNA?

    Symptoms for the determination of antiDNA

    • Body temperature, lymph nodes increase, weight decreases, fatigue appears.
    • With arthritis, inflammation of the joint, manifested by swelling, pain, fever in this area, redness of the skin and impaired mobility.
    • With the appearance of atypical mental and neurological symptoms.
    • With pleurisy or pericarditis of unknown origin.
    • With Raynaud's syndrome, that is, a periodic change in the color of the fingers and hands (redness, pallor, blueness), a violation of their sensitivity and pain.
    • In case of kidney diseases having an immune genesis or changes in the results of a urinalysis (hematuria, proteinuria).
    • With skin symptoms - thickening of the skin, rash, especially after sunbathing.
    • With hemolytic anemia, the destruction of red blood cells with an increase in the level of bilirubin in urine and blood.
    • With neutropenia, a reduced number of neutrophils in the leukocyte formula.
    • With thrombocytopenia, a decrease in the number of platelets in the blood.

    Antibodies to double-stranded DNA: normal

    Normally, the result of the analysis should be negative, and the concentration is 0-25 IU / ml.

    If the result is positive, we can talk about: primary biliary cirrhosis, SLE, infectious mononucleosis, treatment effectiveness (SLE in remission), chronic hepatitis C and B, Sjogren's syndrome, mixed connective tissue disease.

    Double-stranded DNA and antibodies (IgG and IgM immunoglobulins) form an immune complex. It causes a certain symptomatology characteristic of SLE.

    If the result is negative, they say about lupus erythematosus or the absence of SLE.

    What affects the analysis result?

    • High levels of anti-DNA are associated with lupus nephritis, exacerbation of the disease, or lack of control of the disease.
    • Low levels of anti-DNA are associated with the effectiveness of the therapy and reaching the stage of remission of the disease.
    • AntiDNA is a specific indicator of SLE, but can also be observed in other diseases (autoimmune, chronic hepatitis C and B).
    • If antiDNA is absent, this does not exclude the diagnosis of SLE.
    • The detection of anti-DNA in a patient without any symptoms and other criteria for this disease is not interpreted in favor of the diagnosis of SLE.

    Important notes

    A blood test for antibodies to double-stranded DNA is carried out together with the following studies:

    • beta-2-microglobulin,
    • general blood test
    • anti-centromeric antibodies,
    • urinalysis
    • antihistone antibodies

    Two facts about antiDNA

    In addition, anti-DNA appears in the blood due to the following reasons:

    • myeloma
    • SLE, the criterion for the diagnosis of which is to obtain a positive result of the study,
    • viral infection,
    • drug-induced SLE,
    • HIV
    • Sjogren's syndrome,

    Therefore, blood for antibodies to double-stranded DNA is taken quite often.

    Antibodies to double-stranded DNA: what is it, causes

    Antibodies to double-stranded DNA (a-dsDNA) are protein compounds of the blood that destroy the DNA of the body's own cells. They belong to the group of antibodies aimed at destroying the nuclei of their healthy cells - antinuclear antibodies that accompany various pathologies. A characteristic feature of a-dsDNA is that their increased value reflects the presence of systemic lupus erythematosus.

    Systemic lupus erythematosus (SLE) is one of the most serious diseases in which autoimmune processes affect various organs, damaging the connective tissue of the entire body. Modern medicine has the tools to maintain the viability of patients diagnosed with SLE, but the disease remains incurable.

    One of the starting points of the disease is the activation of B-lymphocytes against the body's own cells, which triggers a chain of reactions that sequentially traumatize the tissues of organs. The nature of this process in most cases is unknown, but the most likely causes triggering an autoimmune response are called a combination of factors, including:

    • hereditary predisposition
    • exposure to ultraviolet rays,
    • viral infections (Epstein-Barr, cytomegalovirus, parvovirus),
    • taking medications (Isoniazid, Procainamide, Hydralazine, Chlorpromazine),
    • hormonal disorders (secrete the effects of estrogen)
    • smoking and stress have a provocative role in the presence of other factors.

    Indications and preparation for analysis

    Detection of antibodies to double-stranded DNA is carried out on the basis of a highly sensitive method of laboratory diagnosis - enzyme-linked immunosorbent assay. There are no special requirements for preparation before taking a blood sample, it is necessary to refrain from smoking for 1 hour and from eating 4 hours before the procedure.

    Assignment for analysis is issued if there is suspicion of SLE and control of the patient with SLE. The doctor may suggest the development of the disease if indirect signs are found in other diagnostic tests and if the patient has symptoms. Signs of pathology may not appear immediately, often in the initial stages only headache and weakness are felt, body temperature rises. More specific characteristics:

    • Rashes on the skin begin with a nose bridge, spreading to the cheek area. A “butterfly” shape typical of SLE forms, then the rash can go to the décolleté zone, arms and other parts of the body.
    • Joint pain, sensation of aches in the body. The skin in the area of ​​damaged joints is usually reddened and swollen, the temperature of these areas is higher than the total body temperature. In men, pain can concentrate in the lower back.
    • Sores form in the oral cavity, nails and hair become brittle, focal hair loss occurs. Dense plaques appear on the scalp, a similar rash can be localized in open areas of the body.
    • A wide range of neuropsychiatric pathologies can be manifested by motor impairment, decreased cognitive functions, confusion, anxiety disorders and other phenomena.
    • Detection of blood in the urine as a consequence of a common symptom of SLE - damage to the kidney tissue.
    • Hypersensitivity to sunlight, expressed in exacerbation of skin inflammation.
    • Violations of cardiac rhythm, pain in the chest accompany a number of diseases of the cardiovascular system that develop with SLE.

    When detecting SLE, analysis of a-dsDNA is an accurate marker, but in addition to this, a whole range of studies is carried out, including more than 10 types of various indicators.

    The role of antibodies to native DNA in the development of lupus erythematosus

    Antibodies to native DNA play a key role in the pathogenesis of SLE. The destruction of connective tissue is triggered by autoantibodies attacking the nuclear components of cells. As a result of their interaction, circulating immune complexes are formed that accumulate in the tissues and provoke inflammatory reactions.

    B-lymphocytes producing a-dsDNA are characterized by a violation of not only their protective properties, but also a whole complex of pathological changes. Cells are characterized by hyperactivity, spontaneity of action, defects in the perception of regulatory signals. But not only B-lymphocytes radically change their features. With SLE, all elements of the immune system acquire defects of a different nature.

    Macrophages do not correctly perform their functions of purifying blood from dead cells, thus clogging the internal environment of the body, which provokes an increased response of the immune system - an even greater production of a-dsDNA. Meanwhile, cell death occurs in an accelerated mode, a characteristic feature of SLE is an increased level of apoptosis.

    Violation of properties is observed in NK-killers, T-helpers, peptide information molecules, thymus hormones, stem cell proliferation, and so on. The relationship between the interaction of some elements of the immune system was understood, but most of the mechanisms of pathological changes remain a mystery.

    What to do with a positive test result

    The presence of a-dsDNA at low values ​​does not mean the development of the disease, since antibodies can also be present in a healthy person. When diagnosing, the quantitative component of the indicator is important.

    • Less than 4 U / ml - negative result,
    • From 4 to 10 U / ml - a dubious result,
    • More than 10 units / ml - a positive result.

    When receiving a positive result, it is necessary to exclude factors that affect the indicator (medications and a number of diseases). For this, additional studies are being conducted. If a-dsDNA indicators are not related to other factors, but there is no symptom of SLE, the disease is not diagnosed. Such a patient belongs to a risk group, he will need to be observed by a rheumatologist and periodically examined.

    In the presence of symptoms and a-dsDNA> 10 U / ml, SLE is clearly diagnosed. Today, there are many drugs that contribute to the achievement of deep remission. Each patient needs an individual approach, since the disease is characterized by high variability of its manifestations. An important component is not only medical, but also psychological support, which can be found in public associations of patients suffering from systemic lupus erythematosus.

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