Anti-dsDNA (anti-DNA) or double-stranded DNA antibodies belong to the heterogeneous group of antibodies against double-stranded DNA, and are also laboratory markers of SLE (systemic lupus erythematosus).
Autoantibodies against DNA, which are located inside the nucleus, are called antibodies to double-stranded DNA. The exact cause of their appearance in the blood has not been established.
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 the antibodies produced against their own cells and their components, experts call autoimmune.
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 precisely 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, 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.
SLE - systemic lupus erythematosus
SLE is a serious 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. Lupus manifestations 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.
- 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).
The analysis of antibodies to double-stranded DNA is very informative.
Symptoms of SLE
Common signs of manifestation include enlarged 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, causing 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, that is, 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, 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, and 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; Hard currency; 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 speak of 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 anti-DNA 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
Blood test for antibodies to double-stranded DNA carried out together with the following studies:
- beta-2-microglobulin;
- general blood test;
- anticentromeric antibodies;
- general analysis of urine;
- antihistone antibodies;
- liver tests (alkaline phosphatase, bilirubin, GGT, AST, ALT);
- rheumatic tests (ASLO, C-reactive protein, rheumatoid factor, erythrocyte sedimentation rate);
- antibodies to citrulline peptide (ADC);
- antinuclear antibodies (ANA). They are the most well-studied autoantibodies along with the rheumatoid factor. They were discovered in 1957, and at the same time, researchers proved a connection with SLE. In this case, antibodies to double-stranded DNA are increased;
- anti-SSB and anti-SSA antibodies;
- anti-Sm antibodies;
- anti-sp100 antibodies.
Two facts about antiDNA
In addition, antiDNA 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;
- cytomegalovirus infection;
- Sharp syndrome (mixed connective tissue disease);
- infectious mononucleosis;
- rheumatoid arthritis;
- primary biliary cirrhosis;
- systemic scleroderma;
- viral hepatitis C;
- viral hepatitis B.
Therefore, blood for antibodies to double-stranded DNA is taken quite often.