Antibodies to nuclear antigens, or ANA, is a heterogeneous group of autoantibodies that are directed against elements of their own nuclei. They are detected as a marker of autoimmune diseases and are determined to establish a diagnosis, assess the activity of the pathology and control therapy.
As part of the study, antibodies of classes such as IgM, IgA, IgG are detected.
Study overview
ANA, or antibodies to nuclear antigens, are part of a heterogeneous group of autoantibodies that are directed against elements of their own nuclei. They are determined in the blood of patients with certain autoimmune diseases, for example, systemic connective tissue pathologies, primary biliary cirrhosis, autoimmune pancreatitis, and a number of malignant neoplasms. The analysis for antibodies to the core antigen of ANA viruses is used as a screening for autoimmune pathologies in patients with clinical symptoms of an autoimmune process (unclearby origin, prolonged fever, skin rash, weakness, articular syndrome, etc.).
Such patients need a positive test result for further laboratory testing, including more specific tests for each autoimmune disease (eg, anti-Scl-70 if systemic scleroderma is suspected, anti-mitochondria antibodies if biliary primary cirrhosis is suspected). Needless to say, a negative test result does not rule out the presence of an autoimmune disease.
Antibodies to nuclear antigens are determined in he althy people (3-5%), but if patients are over 65 years old, this figure reaches values from 10 to 37%. In a patient with no evidence of an autoimmune process, a positive result should be interpreted based on additional laboratory, clinical, and history information.
Purpose of the study
Research for antibodies to nuclear antigens is used for a specific purpose:
- As a screening for autoimmune pathologies, such as systemic connective tissue diseases, primary biliary cirrhosis, autoimmune hepatitis, etc.
- For the diagnosis of drug-induced lupus.
- For the diagnosis of systemic lupus erythematosus, prognosis, assessment of disease activity and control of its treatment.
Indications for prescription
A study is prescribed for the following signs of an autoimmune process:
- prolonged fever of unknown origin, joint pain, skin rash, unreasonable fatigue;
- for signs of lupus erythematosus (skin lesions, fever), arthritis/arthralgia, kidney disease, epilepsy, pericarditis, pneumonitis;
- every six months or more frequently during evaluation of a person diagnosed with SLE;
- if Hydralazine, Propafenone, Disopyramide, Procainamide and other drugs associated with the development of drug lupus are prescribed.
Very often detect antibodies to the nuclear antigen of the Epstein-Barr virus.
Change Rules
Analyzed biological material: patient's blood. Special preparation for the analysis is not required, but you need to find out if the patient is drinking any drugs that can distort the results of the analysis. Among them: Pennicillamine, Tocainide, Nitrofurantoin, Methyldopa, Nifedipine, Lovastatin, Carbamazepine, Hydralazine, β-blockers.
If the use of such drugs is recorded, it should be noted in the study form.
Method
Among the most modern methods of analysis of antinuclear antibodies stands out the method of enzyme immunoassay or ELISA. Antinuclear bodies with it are detected using specific nuclear antigens, which are fixed on different solid carriers.
The analysis of antinuclear antibodies by the method of indirect immunofluorescence on cellular means ismore informative than the ELISA test for antinuclear antibodies. Its result is able both to confirm the presence of antinuclear antibodies and to determine the final antibody titer, among other things, to describe the features of the luminescence of the diagnosed antibodies, directly related to the type of those nuclear antigens against which the latter are directed.
Transcription of research results
Reference values of the analysis for antibodies to ANA core antigens: negative. A positive result can be for the following reasons:
- autoimmune pancreatitis;
- systemic lupus erythematosus;
- malignant neoplasms of the lungs and liver;
- autoimmune thyroid disease;
- dermatomyositis/polymyositis;
- mixed connective tissue pathology;
- autoimmune hepatitis;
- myasthenia gravis;
- Raynaud's syndrome;
- interstitial diffuse fibrosis;
- Sjögren's syndrome;
- systemic scleroderma;
- rheumatoid arthritis;
- use of drugs such as Propafenone, Disopyramide, Procainamide, certain ACE inhibitors, Hydralazine, beta-blockers, Chlorpromazine, Propylthiouracil, Simvastatin, Lovastatin, Hydrochlorothiazide, Minocycline, Isoniazid, Phenytoin, Carbamazepine, Lithium.
Reasons for a negative result of the analysis: the norm or violations when taking biological material.
Antibodies to Epstein-Barr nuclear antigen
Epstein-Barr virus, which is part of the type 4 group of herpes, can cause an infectious diseasemononucleosis. And the method for diagnosing its presence is antibodies to the nuclear antigen of this virus IgG (quantitative method, anti-EBNA IgG).
Identifies IgG class antibodies, which are indicative of the patient's infection. Main indications for use: diagnosis of diseases associated with the Epstein-Barr virus (oncological pathologies, chronic infections).
Antibodies to the nuclear antigen of the Epstein-Barr virus IgG class are most often detected in the blood in the period from three to twelve months after infection (approximately 4-6 months), that is, in the late stages after exposure to infection and for a long time (up to several years) they can be detected after illness. The concentration of antibodies increases during recovery. If there are no antibodies to such an antigen in the detection of antibodies to the capsid protein (anti-VCA IgM) of the Epstein-Barr virus, this most likely indicates an ongoing infection.
Blood after venipuncture is taken into an empty test tube to obtain serum. The site of venipuncture is pressed down with cotton wool rolled into a ball until the bleeding stops. If a hematoma has formed at the venipuncture site, warm compresses are prescribed.
Negative result - from 0 to 16 0U/ml. Doubtful - from 16 to 22. Positive - over 22 0U/ml.
When deviating from normal values, a positive result means:
- Epstein-Barr virus infection (detection of antibodies late);
- growing intochronic form of the disease or the stage of reactivation of the disease.
A negative result indicates the following:
- early period of infection (reduced antibody titer);
- no Epstein-Barr virus infection.
Hepatitis B
Indications for research: diagnosis of hepatitis B, previously transferred or monitoring the nature of the pathology.
Research method: chemiluminescent method.
Reference value: negative.
Antibody to the core antigen of hepatitis B is produced. Based on this, the following are distinguished: anti-HBs surface antibodies (to HBsAg antigens that form the envelope of the virus); anti-HBc nuclear antibodies (to the HBc antigen found in the core protein of the virus).
Not always antibodies in the blood indicate the presence of hepatitis B or a disease cured earlier. Their production can also be a consequence of the vaccine made. Among other things, the definition of markers can be conditional on:
- impaired activity of the immune system (including the progression of autoimmune diseases);
- malignant tumors;
- other infectious pathologies.
These results are called false positives, since the presence of antibodies does not lead to the development of hepatitis B.
What factors can affect the result
Uraemia can also lead to a false negative result. Many drugs are associated with the processdevelopment of drug-induced lupus in the body, as well as the appearance of ANA in the blood.
Important notes on this topic
In a patient with symptoms of an autoimmune process, a negative result does not rule out the presence of an autoimmune disease.
ANA is determined in he althy people (3 to 5%) and in the elderly after 65 years (10 to 37%).
If a patient has a positive result without signs of an autoimmune process, it must be interpreted, taking into account additional laboratory, clinical and anamnestic information (such people are 40 times more likely to have SLE).
