Rheumatoid factor

The rheumatoid factor (RF) is a component in the diagnosis of numerous rheumatic and non-rheumatic diseases. It is determined in the blood, usually in the serum . Rheumatoid factors are autoantibodies of various subclasses (IgM, IgG, IgA, IgE) that are directed against certain areas of the body's own immunoglobulins of class G ( IgG ) (against the Fc fragment of IgG). The term is often used in the plural (ie "rheumatoid factor s ").

The detection of a rheumatoid factor in the blood serum makes a rheumatic disease more likely, but it does not prove it. A negative rheumatoid factor also makes rheumatoid arthritis less likely, but does not rule it out. One speaks of “ seronegative rheumatoid arthritis” when the disease “rheumatism” (rheumatoid arthritis) is present, but the rheumatoid factor cannot be detected. Rheumatoid factors are also found in low concentrations in around 5% of healthy people (10% in people over 60 years of age), in Sjögren's syndrome and other collagenoses , in liver diseases (e.g. hepatitis C) or chronic infectious diseases.

A significant improvement in laboratory diagnosis of rheumatoid arthritis, the discovery of citrullinated antigens and the A ntikörper against c itrullinierte P eptid- / protein A ntigene ( ACPA brought) and their importance for the diagnosis of rheumatoid arthritis. These natural antigens are found within the inflamed synovial tissue and as circulating antigens in the synovial fluid of patients with proven rheumatoid arthritis; the antibodies are known as biomarkers for rheumatoid arthritis.

The most widespread here is an ELISA laboratory test that detects artificial cyclic citrullinated peptides. This detection of so-called anti-CCP antibodies has led to a significant improvement in laboratory diagnostics of rheumatoid arthritis, including the diagnosis of early stages of the disease. Antibodies to citrullinated peptides may be detected years before the onset of disease. However, it has not yet been possible to show any pathogenetic significance for CCP antibodies. The connection between the anti-CCP antibody titer and the disease activity of rheumatoid arthritis has also not been proven. The CCP antibodies are therefore not suitable as parameters of the course of the disease.

A new type of ELISA test based on the mutated citrullinated vimentin, MCV, offers a good diagnostic sensitivity comparable to the anti-CCP-ELISA with a slightly lower specificity . Initial studies with this test system show the connection between the anti-MCV antibody titer and the disease activity and the severity of rheumatoid arthritis. The anti-MCV antibodies could thus have the advantage over the anti-CCP antibodies of a correlation with the disease activity and could possibly also be suitable for monitoring the progress of therapy in rheumatoid arthritis. However, further results from other independent studies should be awaited for a final assessment.

It was discovered in 1940 by Erik Waaler in Norway and again in 1948 by Harry M. Rose and Charles Ragan in New York.

Individual evidence

1. ↑ Guidelines of the German Society for Rheumatology, Chapter 2.2. Laboratory diagnostics .
2. ↑ E. Feist, K. Egerer, G.-R. Burmester, Z Rheumatol 2007, 66: 212-218: Autoantibody profiles in rheumatoid arthritis. https://link.springer.com/article/10.1007%2Fs00393-007-0159-3 .
3. ↑ Roland PN et al. Antibodies to mutated citrullinated vimentin for diagnosing rheumatoid arthritis in anti-CCP-negative patients and for monitoring infliximab therapy. Arthritis Re Ther. 2008 Dec 10; 10 (6): R142. http://arthritis-research.com/content/10/6/R142 .
4. ^ Waaler, On the occurrence of a factor in human serum activating the specific agglutination of sheep blood corpuscules, Acta Path. Microbiol. Scand., Vol. 17, 1940, 172-178.
5. ^ HM Rose, C. Ragan, E. Pearce, MO Lipman: Differential agglutination of normal and sensitized sheep erythrocytes by sera of patients with rheumatoid arthritis, Proc. Soc. Exp. Biolog. Med., Vol. 68, 1949, pp. 1-11.

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !