Citrullinated vimentin antibodies (Anti-MSV)
Why this test?
For early diagnosis of rheumatoid arthritis, making its prognosis and monitoring its treatment.
In what cases is it prescribed?
With symptoms of joint syndrome: pain and deformation in the joint area (symmetric damage mainly to the small joints of the hands and feet, it is also possible to involve the knee, hip and other large joints), limitation of active and passive mobility (morning stiffness lasting more than 1 hour), edema and hyperemia of the skin over the joints - especially if the result of the study for rheumatoid factor (RF) is negative.
When examining a patient with a burdened hereditary history of rheumatoid arthritis.
Antibodies to citrullinated vimentin (anti-MCV) are autoantibodies directed against the body's own vimentin protein. They are more often found in the blood of patients with rheumatoid arthritis (RA) and are considered as a clinical and laboratory marker of this disease.
Vimentin is one of the proteins of the cytoskeleton, characteristic of cells of mesenchymal origin, including macrophages and fibroblasts, found in large quantities in the synovial membrane of joints. It belongs to the intermediate filamentous structures and normally performs a structural role. Under the influence of inflammatory mediators, vimentin undergoes citrullination - a process in which the amino acid arginine in vimentin is converted into citrulline. Citrullinated vimentin acts as an antigen for autoantibodies in rheumatoid arthritis. One of the biochemical variants of citrullinated vimentin has the greatest immunogenicity - modified citrullinated vimentin, in the molecule of which glycine amino acid residues are replaced by arginine.
Detection of antibodies to modified citrullinated vimentin (anti-MCV, from the English Anti-modified citrullinated vimentin antibodies) is a characteristic feature of rheumatoid arthritis.
Serological studies play a huge role in the differential diagnosis of joint syndrome and the diagnosis of RA. Despite some features of diseases that occur with damage to the joints, their differential diagnosis cannot be carried out on the basis of only the clinical picture. On the other hand, different diseases are characterized by different prognosis and treatment tactics. Therefore, the specificity of the test is of great importance when choosing a laboratory test that allows differential diagnosis of joint syndrome and diagnosis of RA. The specificity of the analysis for anti-MCV reaches 98%. This means that a positive test result in a patient with clinical signs of RA allows to confirm the diagnosis. The specificity of the antiMCV test for RA is comparable to the specificity of the test for antibodies to cyclic citrulline-containing peptide (anti-CCP, specificity about 92-98%) and much higher than the test for rheumatoid factor (RF, specificity 70%). Due to this advantage, this analysis was included in the new (2010) diagnostic criteria for RA, along with the rheumatoid factor and some other laboratory parameters.
It is known that immunological disorders characteristic of RA appear long before the clinical symptoms of this disease. Thus, anti-MCV can be detected 10-15 years before the development of the disease. Therefore, the detection of anti-MCV in the patient's blood, even without any signs of joint damage, should be taken into account by a rheumatologist, especially with a hereditary anamnesis aggravated by RA. However, it should be noted that a positive anti-MCV test result is not a sufficient diagnostic criterion for making a diagnosis of RA.
The anti-MCV test is particularly useful in the examination of a patient with recent RA in the absence of a clear clinical picture of the disease. Quite often, at the early stage of the disease, rheumatoid factor (RF), one of the main criteria for RA, is not detected, which complicates the diagnosis. In contrast, anti-MCV can be detected in most patients with early RA. The sensitivity of the anti-MCV test in a patient with severe symptoms of RA increases to 70-84%. At the same time, the combination of two studies - anti-MCV and CCP - has the highest sensitivity for early RA.
Analysis of anti-MCV is also necessary for making a prognosis of RA. The presence of these antibodies is associated with the development of destructive changes in the joints and the rapid progression of RA. The concentration of anti-MCV more accurately reflects disease activity than the concentration of anti-CCP. With immunosuppressive therapy, the anti-MCV titer gradually decreases and the test result may become negative. Therefore, the anti-MCV test can be used to monitor treatment. For the same reason, it is recommended to donate blood for research before starting RA treatment.
Despite the fact that anti-MCVs are most characteristic of RA, they can also be detected in systemic lupus erythematosus, Sjögren's syndrome and psoriatic arthritis, as well as some other autoimmune diseases. The results of the study must be interpreted taking into account additional clinical, laboratory and instrumental data.