Analysis on acc. Accp: what is it in the blood, the norm and deviations in the analysis, as evidenced by the increase in the Antibody to the cyclic citrulline containing peptide

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A blood test for ACCP (ACCP, anti-CCP, A-CCP is the short name of the diagnostic test) is used to identify individual pathological conditions not only at the height of clinical symptoms, but also in advance, if there are any prerequisites for this (the presence of a disease in relatives). For example, ACCP is considered the "gold" standard, the most informative marker of rheumatoid arthritis (RA). This abbreviation is deciphered as follows: antibodies (AT) to cyclic citrullinated peptide. Therefore, we can say this: ACCP - antibodies directed against the proteins (autoantigens) of the synovial membrane (synovia) that have been changed as a result of the inflammatory reaction, which contain the atypical amino acid citrulline.

Cyclic citrullinated peptide - what is it?

Citrulline itself, although an amino acid, behaves differently from other (standard) amino acids. Not penetrating into proteins during their formation, citrulline remains aloof from building proteins, is not included in their category, however, it has a certain and, it should be noted, considerable physiological function: it actively participates in metabolic processes (urea), maintaining nitrogen balance in body. Citrulline is a product of the metabolic reactions of arginine (nitrogen donator), in other cases, the transition of arginine to citrulline starts the production of cyclic citrullinated peptides. The citrullination reaction is noted in the course of various biochemical transformations, both physiological and pathological.

Perceiving the cyclic citrullinated peptide as something alien, the immune system, through local plasma cells of the inflamed synovial membrane, responds with the production of appropriate immunoglobulins, the purpose of which is to attack the "enemy" and destroy it by forming the "antigen-antibody" complex. This is how the autoimmune process develops.

Experts believe that proteins obtained in synovia during citrullination trigger the immune response. The reason for the formation of all antibodies to citrulline is the modification of some proteins (vimentin, fibrin, etc.), when amino acid residues of citrulline appear in the structural structure of these proteins. Protein modification occurs during the inflammatory response in the synovium in rheumatoid arthritis.

The main thing is to know the norm?

Most often, for some reason, readers first of all seek to find out the rate of the indicator, without delving into the essence of the problem. Probably, in order to compare the values ​​​​with the result of a blood test received on hand, and then figure it out: what's what. It may be necessary to somewhat disappoint the overly curious: any sources can only provide indicative norms - they depend on the method of conducting the study, as well as on the reference intervals adopted by a particular laboratory (in which, by the way, the answers should be clarified). Nevertheless, the desire of readers is the law, therefore, it is probably worth satisfying the interest of our respected public and, before talking about antibodies to cyclic citrulline peptide, provide the values ​​​​of their norm.

For example, the answer after the study of ACCP:

• The immunofluorescent method can be as follows: "negative" - ​​this means up to 5 U / ml (normal). At the same time, the threshold values ​​of ACCP = 5 U/ml give grounds to continue the examination of the patient;
• With the help of chemiluminescent immunoassay - up to 17 U / ml.

When testing by enzyme-linked immunosorbent assay (ELISA) using 2nd generation test systems (the "gold" standard for detecting ACCP), slightly different results can be expected:

Deciphering the results

Of course, the doctor is engaged in deciphering and interpreting the results, as in cases of other laboratory studies, however, it is pointless to make a secret of this: those interested will still begin to search for sources of knowledge, so it is advisable to give the main provisions:

• The determination of antibodies to CCP significantly increases the likelihood of diagnosing such a serious pathological process as rheumatoid arthritis. In the stage of early RA, the detection of ACCP shows (together with other tests - RF) a rather high sensitivity (80 - 85%);

• The study of the anti-CCP titer and comparison of the results with the nature of the disease and inflammatory process should be carried out, guided by the classification diagnostic criteria for RA (ACR / EULAR). However, as a rule, a sharply increased titer in the blood test corresponds to the high activity of the process, the progression of symptoms and the severe course of the disease;
• The negative value of the results, on the contrary, is encouraging: the risk of getting RA is small, but if this happens, the process will be slow and not so painful;
• The ACCP study is recommended to be carried out with other laboratory parameters: RF, of course, antinuclear factor, as well as HLA typing in order to detect the HLA-B27 antigen (a marker of Bechterew's disease - ankylosing spondylitis).

And yet, I would like to remind readers once again that it is not very useful to figure out where it is “positive” and where it is “negative”, based on the quantitative values ​​of the ACCP given in various sources. Answers to questions regarding the norm should be sought in the laboratory that tested the biological material.

Antibodies to CCP

Immunoglobulins produced in response to proteins containing citrulline belong mainly to class G (IgG). They show a rather high specificity and are determined in 80-90% of patients who are not yet particularly aware of the development of RA, one might say, long before the onset of the disease, even at the preclinical stage.

As you know, rheumatoid arthritis is classified as a very common systemic pathological process of an autoimmune nature, affecting up to 2% of the world's inhabitants. However, the symptoms that appear in rheumatoid arthritis may be evidence of other rheumatic diseases, which makes differential diagnosis difficult.

A-CCPs are found much more often and earlier than the marker that is familiar to everyone, which is called. His study is primarily resorted to when RA is suspected, but he gives a signal about pathological changes only after some time (≈ 45 days) from the onset of their development. The study of ACCP shows not only the height of the disease, a blood test that detects ACCP (titer - elevated) can signal an approaching danger in a year or two, which is very important in terms of identifying the disease at the initial stage and its early treatment, until irreversible changes have occurred in the joints. degenerative and destructive changes.

Today it is the newest method for diagnosing RA

The blood test, which involves the detection and study of antibodies to cyclic citrulline peptide (ACCP), has gained the most popularity among new developments and methods. This method of diagnosing rheumatoid arthritis today has taken the place of the second immunological standard after rheumatoid factor, which still occupies a leading position, due to the ease of implementation and availability of the test. The representatives of this category (antiperinuclear factor and antikeratin antibodies), studied back in the middle of the last century, were not widely used in laboratory diagnostics before the introduction of enzyme-linked immunosorbent assay (ELISA) methods. ELISA enabled ACCP to prove itself as an excellent RA diagnostician. The significance of this analysis lies in:

1. Production and appearance in the blood serum of immunoglobulins directed to the cyclic citrullinated peptide (linear peptides do not provide such a high sensitivity of the test) in the blood plasma approximately a year before the onset of the disease (the sensitivity of the analysis in the earliest period of the development of the process reaches 75 - 80%);
2. High specificity in the presence of rheumatoid arthritis (up to 90 - 95%);
3. Identification of these immunoglobulins in patients with a negative result for the rheumatoid factor, that is, a person donated blood, a study on the RF was carried out, but nothing suspicious was found (the value of the RF is negative or does not exceed the permissible norm, if the analysis is quantitative);
4. The use of the test for ACCP in prognostic terms (a strongly elevated indicator makes one think of a more severe form of RA).

Thus, a blood test that looks for antibodies to cyclic citrullinated peptide is not yet prescribed to everyone. Since it is ideally performed using enzyme immunoassay, the laboratory should have the equipment and testing systems for this study. Send the patient to the laboratory for a similar purpose, if there is evidence for this:

• Suspicion of the development of rheumatoid arthritis (along with other biochemical tests and, above all, RF);
• Calculation of the risk of developing RA if the disease occurs in relatives;
• Monitoring and forecasting the course of already established RA;
• Determination of the quality (efficiency) of treatment.

An elevated titer of antibodies to CCP, of course, first of all indicates the "origin" or development of rheumatoid arthritis. However, sometimes, if the result is increased, but no more signs of developing RA are noted, the doctor may suspect another pathology of the connective tissue, for example,.

How were the target antigens found?

The discovery of citrullinated antigens, as well as immunoglobulins aimed at their destruction, has been of great benefit in the diagnosis of certain diseases. Antigens (AGs) containing citrulline were recognized during the search and then the study of specific markers of rheumatoid arthritis (antikeratin antibodies - AKA, which became the starting point in this case). However, in rheumatoid arthritis, as in the case of many other conditions, before the pathological process manifests itself with a mass of unpleasant symptoms, something must happen in the body (in rheumatoid arthritis, changes primarily affect the joints, although it should be recalled: there are also extra-articular variants of RA).

During the study, it was found that antibodies against keratin notice only those proteins that contain citrulline (for example, filaggrin - it is the target antigen for AKA), while they do not react to other proteins. However, as it turned out, filaggrin in the joints, just like in other internal organs, never happens, it can only be found in the epithelium, which undergoes keratinization. Then what's the matter? Further studies made it possible to answer this question: antikeratin antibodies distinguish only citrullinated filaggrins, they do not notice other forms. Later it was found that these antibodies are able to "recognize" the CCP antigens. The citrullinization process itself may represent the transition of arginine to citrulline through the removal of the amino group from its molecule (deamination).

Meanwhile, the citrullinization reaction itself is not specific for rheumatoid arthritis, and in general, it is not characteristic of synovial proteins. A similar reaction can occur in various tissues during inflammation, programmed (genetically) cell death - apoptosis, metaplasia, cellular rearrangement in tissues during aging. But the response of the immune system, which is directly related to the production of ACCP, depends on how much, to what extent, citrullinization occurred in proteins. For example, such a bad habit as smoking has long been suspected of causing the development of rheumatoid arthritis. Indeed, citrullination of antigens, the formation of antibodies to the cyclic citrullinated peptide and other autoantibodies of this category (anti-citrulline) increase in the lung connective tissue.

In the process of studying target antigens, it was found that autoantibodies recognized in rheumatoid arthritis, for the most part, are citrullinated "fragments" of various proteins, including filaggrin, which was discussed above, vimentin, keratin, fibrinogen. By the way, fibrinogen and fibrin are also classified as citrullinated AGs. In addition, during the experiments, a cross-reactivity (cross-reaction) between filaggrin and citrullinated fibrin was noticed, which makes it possible for the latter to start and accelerate the production of ACCP to these amino acids, because the concentration of citrullinated fibrin in the inner layer of the articular sac (synovium) is quite high during inflammation .

Diagnosis in rheumatology is extremely difficult. Anti-cyclic citrullinated peptide antibodies isolated during serological testing of a blood product from patients with rheumatoid arthritis (RA) are considered the gold standard for diagnosis. Early detection of this severe autoimmune lesion of the musculoskeletal system will help prevent or reduce degenerative-dystrophic changes in it. But the norm of ACCP does not always indicate the absence of rheumatoid arthritis.

In the ratio of antibodies to cyclic citrullinated peptide in serology, an accurate diagnosis of rheumatoid arthritis can be made.

What it is?

ACCP in rheumatoid arthritis - protein fractions, where the structural elements are amino acids, among which arginine is found - a building block of human genetic material. A derivative of this amino acid is citrulline, which is included in the urea formation cycle. In a healthy person, citrulline is not involved in protein synthesis and is soon excreted from the body without joining the metabolism. The level of Anti-CCP in the blood increases if the patient has rheumatoid arthritis. At the same time, citrulline is directly involved in the apoptotic processes of body cell death.

Why is analysis needed?

If the patient has characteristic complaints during the initial examination and history taking, he is prescribed an x-ray examination. When traces of degenerative-dystrophic phenomena in the joints are visible on radiographs, confirmation of the diagnosis with the help of laboratory tests is necessary. A positive analysis for ACCP in rheumatoid arthritis means the need to start specific treatment. Data from a general and biochemical blood test can only confirm the diagnosis, but not refute it.

Advantages of studying antibodies to citrulline peptide

Deciphering the level of antibodies on the CPU indicates the presence in the synovial fluid of the joints of specific immune complexes that provoke the disease. The limits of the indicators signal the severity of the current. Their increase indicates rheumatoid arthritis. The acute course of this rheumatological pathology requires an immediate initiation of therapy. And since the express test is performed quite quickly, and the laboratory assistant does not need specific equipment to take the biomaterial, the diagnosis is obtained as soon as possible. The gradation of the concentration of ACCP makes it possible to judge a weakly positive or strongly positive result.

Preparation for the event

Material sampling for Anti CCP is performed using venipuncture (venous blood sampling). The general practitioner is obliged to provide the patient with recommendations on special preparation for the test:

• On the day of the visit to the laboratory, the patient must refrain from food and drink. You can only drink a glass of clean water.
• A few days before the analysis, the patient completely excludes fried and fatty foods, alcohol and dishes with dyes from the menu.
• The patient should not use dietary supplements and vitamin complexes during the week before the start of the laboratory study.
• It is desirable to exclude any physical activity, physiotherapy procedures that increase the body temperature and accelerate the course of metabolic processes.

How is citrulline peptide tested?

The blood sampling procedure takes place in a laboratory where strict sterility is adhered to. The skin of the upper third of the inner surface of the forearm is treated twice with a cotton swab moistened with an alcohol solution. A special tourniquet is applied to the shoulder. The patient must make flexion movements with the fingers of the hand - thus increasing the blood flow in the vessels of the hand. The laboratory assistant uses special vacuum systems to take biological material. The latter is delivered to the laboratory and analyzed within a few hours. Blood serum can be stored for another seven days at a certain temperature. The study is carried out using an enzyme immunoassay analyzer, then its decoding is provided.

ASSR norm

If the concentration of antibodies to cyclic citrulline peptide reaches 3 units/ml, this is a negative indicator. This figure is considered the norm of a healthy person. The upper limit of the normal level of antibodies to the cyclic citrullinated peptide is up to 5 U / ml. The norm for women is the same as for men. But in pregnant women and children (during the formation of the musculoskeletal system), the indicators can reach 48-49 U / ml, in the elderly - 50. The table shows the value of the concentration of antibodies:

It is desirable to confirm the analysis with data on the level of rheumatoid factor (RF), a marker of an immunoglobulin nature. There is also a possibility that the patient has seronegative rheumatoid arthritis, which cannot be established using this test.

Rheumatoid arthritis is a chronic disease belonging to the group of autoimmune pathologies. The disease systemically affects connective tissues, mainly articular. In this case, their destruction occurs similarly to progressive erosive-destructive polyarthritis. The nature of the disease is not clear. The percentage of cases is approximately 0.5-1%.

Rheumatoid arthritis must be diagnosed as early as possible in order to apply modern methods of therapy in a timely manner. In an advanced stage, the disease can lead to disability and even disability. Therefore, do not postpone the examination for a long time.

Types of diagnostics

There are two main types of diagnostics:

1. Analysis for rheumatoid factor (RF).
2. Analysis of antibodies to cyclic citrullinated peptide (ACCP).

RF is used quite rarely, as it is specific and allows you to identify other articular pathologies. The second type of study makes it possible to more accurately determine the presence of the disease and its severity.

The study is considered the most modern method for detecting antibodies to cyclic citrullinated peptide. Today it is the most accurate way to diagnose the early stages of the disease.

ACCPs begin to be produced in the human body at the initial stage of the disease. This occurs several years before the first symptoms of the pathology appear.

Other blood test options, such as rheumatic tests and rheumatoid factor, detect the presence of the disease at later stages, when it is almost impossible to reverse the process.

Description of the ACCP blood test

Citrulline is a substance produced as a result of metabolic processes in the body. It arises from an amino acid as a consequence of biochemical reactions. In the normal state of the body, citrulline is completely eliminated from it, without participating in the production of protein.

Rheumatoid arthritis changes the enzymatic composition of human blood. The body perceives the peptide, which is a component of citrulline, as a foreign object. As soon as it appears, the body's immune system begins to actively produce specific antibodies aimed at combating the cyclic citrullinated peptide.

The ACCP test gives a specific result that allows you to determine the presence of arthritis. In fact, the analysis is a marker of the disease. ACCP is a heterogeneous group of antibodies that detect antigens of proteins containing citrulline.

Symptoms of pathology

Rheumatoid arthritis is one of the most common autoimmune chronic joint pathologies. The main characteristics are inflammatory processes in the joints, as well as dystrophic, degenerative changes in them. In addition, a number of other symptoms are typical for the disease.

The main symptom of the disease is damage to the articular tissues. The progression of rheumatoid arthritis leads to the following consequences:

1. Joint pain.

2. Redness of the skin in the affected joints.

3. Edema of tissues.

4. Limited movement of connective tissues.

5. Stiffness in the joint area in the morning.

6. Failure of the segments of the joint.

Early detection

The development of pathology leads to progressive inflammation of the joint, which causes deformation and limited mobility of the affected limbs.

The early stages of rheumatoid arthritis can only be detected using differential diagnostic techniques. The specialist needs to pay special attention to symptoms typical of arthritis, inflammatory processes in the joints, the presence of CCP antibodies in the blood and rheumatoid factor. The latter, however, as mentioned above, is used quite rarely in the diagnosis of rheumatoid arthritis, as it can appear against the background of many other specific diseases.

Advantages

The specificity of the ACCP blood test is very high and is up to 98%. It is with such a degree of probability that he will reveal arthritis. Therefore, it occupies a leading position in the diagnosis of arthritis, surpassing other types of tests for rheumatic tests in accuracy.

In addition to determining the presence of rheumatism, the analysis makes it possible to evaluate the form of arthritis, which can be erosive and non-erosive. Elevated levels of ACCP indicate serious damage to the cartilage of the articular tissue. This is what distinguishes such patients from people in whom ACCP is normal.

This type of study is also used to predict the rate of destruction of the cartilage of the connective tissue in the initial stages of the development of pathology. The appearance of ACCP indicates the progressive nature of the disease.

As a rule, an integrated approach to examination is used in the diagnosis of arthritis. The diagnosis is made on the basis of both the analysis for ACCP and rheumatoid factor. This allows for early detection of pathology, to prevent the development of dystrophic and degenerative processes in the joints, by prescribing adequate therapy.

Description of the procedure

Blood sampling for research is carried out from a vein. In order to carry out the tests, it is necessary to obtain blood serum, so it is centrifuged. The resulting substance is stored for a week at a temperature of 2 to 8 degrees. The study of serum is carried out directly in a test tube, using the technique of scattering a laser beam in a liquid medium.

Deciphering the results

When deciphering a blood test for ACCP, an ACCP indicator of 3 units / ml is considered normal. Exceeding this value reliably indicates the presence of rheumatoid arthritis in the body. Depending on the degree of increase in the index, the severity of the articular lesion due to the inflammatory process is determined.

The value of ACCP in rheumatoid arthritis, obtained in the course of a blood test, also makes it possible to predict the progression of the disease and develop a therapeutic strategy.

It should be taken into account that the ACCP value will remain high even after the patient's condition improves. In this regard, it will not be possible to evaluate the effectiveness of the treatment using this type of analysis.

Purpose of the analysis

The main objectives of the analysis on ACCP are:

1. Early diagnosis of rheumatoid arthritis. We are talking about identifying a disease that arose less than six months ago.

2. Identification of pathology at stages of development from six months to a year.

3. For the purpose of diagnosing seronegative forms of pathology in case the rheumatoid factor gives a negative result.

4. As part of the differential diagnosis of not only arthritis, but also other joint lesions and diseases associated with them.

5. Assessment of possible risks of deformity and degeneration of the joint in the early stages of the development of rheumatoid arthritis.

6. Drawing up an optimal and effective treatment regimen for the disease.

Since patients with various diseases of a rheumatic nature have an articular lesion, diagnostics for rheumatic tests does not give accurate results. Therefore, most often, patients are offered to undergo a blood test for ACCP.

Study preparation

A blood test for ACCP must be taken after certain training prescribed by the attending physician. The rules are quite simple to follow, but they will allow you to obtain reliable and qualitative indicators of the analysis.

The rules for preparing for analysis at ACCP prescribe the following:

1. The day before blood sampling, you must stop smoking and drinking alcoholic beverages.

2. One day before the test, you can not eat dishes from fast food restaurants, as well as any fatty foods and foods that are difficult to digest by the body.

3. Try to avoid emotional upheavals, stress and worries.

4. It is necessary to exclude heavy physical exertion a day before the expected time for the test. This applies to both work and training.

5. Before taking the test, you need to calm down and sleep well, tune in a positive way.

6. During the day before the blood test for ACCP, it is necessary to stop taking all medications, with the exception of those that are vital. If it is not possible to exclude the use of drugs, it is necessary to inform the laboratory assistant and the attending physician about this.

7. It is necessary to donate blood on an empty stomach, so it is better to postpone breakfast for a while after taking the material. It is acceptable to drink a small amount of pure non-carbonated water. The last meal should be at least 10 hours before blood donation.

A blood test for ACCP and interpretation, therefore, are very important in the diagnosis of rheumatoid arthritis in the early stages of the development of the disease. This allows you to prescribe an effective treatment that can stop degenerative, destructive processes in the joints and enable the patient to lead a full life.

[13-014 ] Anti-cyclic citrulline-containing peptide, IgG

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Antibodies to the cyclic citrulline-containing peptide, IgG, are a heterogeneous group of IgG autoantibodies that recognize antigenic determinants of filaggrin and other proteins containing the atypical amino acid citrulline.

Russian synonyms

ACCP, anti-CCP-AT, anti-CCP, anti-SSR.

SynonymsEnglish

Anti-CCP, cyclic citrullinated peptide antibody, Anti-citrullinated protein antibody, Ig G; Soft-CCP, AntiCCP Antibody, Anticitrullinated Protein/Peptide Antibody (ACPA).

Research method

Electrochemiluminescent immunoassay (ECLIA).

Determination range: 7 - 500 U/ml.

Units

U / ml (unit per milliliter).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for research?

Do not smoke for 30 minutes prior to the study.

General information about the study

Antibodies to the cyclic citrulline-containing peptide, IgG, are currently one of the most informative markers of early rheumatoid arthritis. ACCPs belong predominantly to the IgG class and are found in the blood at the earliest stages of rheumatoid arthritis (1-2 years before the onset of the first symptoms).

Rheumatoid arthritis is the most common chronic autoimmune disease characterized by damage to peripheral joints with the development of erosive-destructive changes in them and a wide range of extra-articular manifestations. A characteristic feature of rheumatoid arthritis is a symmetrical lesion of the joints of the hands, feet, wrist, elbow, shoulder, knee and ankle joints. Soreness, swelling, redness of the skin over the affected joints, limitation of movements and, as a result, dysfunction of the joints are noted. One of the important symptoms of rheumatoid arthritis is morning stiffness in the joints lasting more than one hour. Progressive inflammation of the joints leads to a significant limitation of their mobility with the development of articular abnormalities.

Initially, with damage to the joints in the form of arthritis, there is a need for differential diagnosis. At the same time, it is necessary to pay attention to the typical signs of rheumatoid arthritis, the development of an erosive process in the joints of the hands, rheumatoid factor, and especially to antibodies to CCP. Rheumatoid factor is not specific enough and can be detected in other autoimmune diseases and chronic infections, while antibodies to cyclic citrulline-containing peptide have a higher specificity (98%) and diagnostic significance for the detection of rheumatoid arthritis. The test also allows you to differentiate between erosive and non-erosive forms of the disease. In patients with elevated levels of antibodies to CCP, a greater degree of damage to the cartilage of the joint is noted compared to patients in whose blood these antibodies are absent. This can be used to predict the rate of joint destruction at the stage of early rheumatoid arthritis, which allows us to consider the detection of ACCP as one of the factors for an unfavorable prognosis of this disease. The joint determination of rheumatoid factor and ACCP allows diagnosing rheumatoid arthritis at an early stage, prescribing timely therapy and preventing severe destructive changes in the joints.

What is research used for?

• To diagnose rheumatoid arthritis at a very early stage (disease duration
• For the diagnosis of seronegative forms of rheumatoid arthritis (when the test for rheumatoid factor is negative).
• For differential diagnosis of rheumatoid arthritis and other autoimmune diseases with articular syndrome.
• To assess the risk of developing joint destruction in patients with early rheumatoid arthritis.

When is the study scheduled?

• In some rheumatic diseases, articular syndrome occurs (pain, swelling in the joints, morning stiffness, local reddening of the skin), which can complicate the correct diagnosis, especially in the early stages of the disease. In this case, the analysis helps to make a differential diagnosis, since it has a high specificity (up to 98%) and sensitivity (up to 70%) for detecting rheumatoid arthritis even at the earliest stages of the disease, when only a few symptoms are present.
• When planning therapy for rheumatoid arthritis. Patients whose blood contains ACCP are characterized by a more aggressive course of the disease with rapid progression of erosions in the joints, therefore, in the early stages of the disease, it is necessary to prescribe adequate therapy to prevent the development of irreversible changes in the joints (deformities, ankylosis).

What do the results mean?

Reference values: 0 - 17 U/ml.

Causes of elevated levels of ACCP

• Rheumatoid arthritis.
• Juvenile idiopathic arthritis.
• Some connective tissue diseases (systemic lupus erythematosus, systemic scleroderma, Sjögren's syndrome).
• Systemic vasculitis (Wegener's granulomatosis).
• Autoimmune thyroiditis.

What can influence the result?

In patients with hypergamma globulinemia, the test result may be false negative.

Important Notes

• To monitor the effectiveness of rheumatoid arthritis therapy, this analysis is inappropriate, since against the background of the use of most basic and symptomatic drugs, there is no significant decrease in the level of ACCP.
• ACCP appear in the blood serum 1.5 years before the onset of symptoms of rheumatoid arthritis.

• Antikeratin antibodies (AKA)
• antiperinuclear factor
• Anti-citrullinated vimentin (anti-MCV) antibodies
• Circulating immune complexes (CIC)

Who orders the study?

Rheumatologist, therapist, traumatologist, orthopedist, surgeon, general practitioner.

Literature

• Rheumatology: National Guide / ed. E.L. Nasonova, V.A. Nasonova. - M. : GEOTAR-Media, 2008. - 720 p.
• Clinical rheumatology (guide for practitioners) / ed. Corresponding Member of the Russian Academy of Medical Sciences Professor V.I. Mazurova. - St. Petersburg: OOO "Foliant Publishing House", 2001. - 416 p.
• Clinical Guide to Laboratory Tests / Ed. WELL. Tiitsa. – M.: Unimed-press, 2003. – 942 p.
• Journal "Handbook of the head of the clinical diagnostic laboratory" No. 6, 2010. Modern laboratory diagnostics of rheumatoid arthritis.
• EUROIMMUN Medizniche Labordiagnostika AG. Anti-CCP ELISA (IgG). 2009 (instruction for determining ACCP).
• Anti-CCP antibody testing as a diagnostic and prognostic tool in rheumatoid arthritis.
• Oxford Journals Medicine QJM: An International Journal of Medicine Volume 100, Issue 4 Pp. 193-201.

Rheumatoid arthritis affects approximately 1% of the population. Antibodies to cyclic citrullinated peptide (ACCP), discovered at the beginning of the 21st century, have become the gold standard for the differential diagnosis of this severe systemic autoimmune disease that provokes degenerative-dystrophic phenomena in the joints of the entire musculoskeletal system and has many extra-articular symptoms.

What is this substance?

Cyclic citrulline peptide has a protein nature. The precursor of CCP is the amino acid arginine. As a result of its modification, citrulline is formed. In a healthy person, this protein does not enter the metabolic cycle and is excreted from the body through the excretory organs. In patients who have been diagnosed with rheumatoid arthritis, there is an increase in plasma CCP. The citrullinated protein is involved in cell death as well as their differentiation into specific tissue structures.

What is the nature of antibodies to cyclic citrullinated peptide?

By labeling immune cells on preparations with dyes, scientists discovered vimentin or citrulline antigen. Anti-keratin antibodies, specific markers of RA, were a potential method of combating it. The formation and activation of antibodies stimulates the fibrin protein, which accumulates in large quantities in the synovium of the inflamed joint. ACCP are determined even in the seronegative variant of the course of RA.

Indications for analysis

The costly anticitrullinated cyclic peptide hemotest is recommended if there is radiological evidence in a patient with rheumatoid arthritis. The diagnosis can be confirmed by a general and biochemical blood test, a study of a sample of the synovial fluid of the joint. A positive transcript of the test for ACCP is an absolute proof of the presence of RA.

Preparation for the examination

Since the blood test is taken from a vein, the patient should prepare for it as follows:

1. On the day of donation, a person cannot eat or drink anything except water.
2. For several days, fatty and fried foods, alcoholic beverages are excluded from the diet.
3. The use of dietary supplements should be avoided.
4. It is important to control the temperature and condition of the body.
5. More than 12 hours must elapse after physiotherapy or physical activity before the analysis is carried out.

Citrullinated fibrin derivatives accumulate in the synovium during inflammation of the joint. Immune bodies to the citrulline-containing peptide enter directly into the plasma. That is why, for analysis, not synovial fluid is taken, but venous blood.

Substrate sampling

The procedure is performed under sterile laboratory conditions. The injection area of ​​​​the syringe is disinfected several times with alcohol. A tourniquet is applied above the puncture site. The patient is asked to clench his fingers into a fist several times to fill the veins of the arm. Blood is drawn into a vacuum system and sent for laboratory analysis. After removing the needle, the patient holds a cotton swab moistened with an antiseptic at the puncture site for several minutes, holding his elbow. Blood plasma can be stored for about a week. The results are interpreted in vitro using enzyme immunoassay (ELISA).

Transcript of results

Cyclic citrulline in the synovium of the joint in rheumatoid arthritis, as well as the presence of antibodies to it in the blood, indicate an acute course of the pathology and the need for urgent medical care. Allocate positive, false positive and negative results of the analysis.