RHEMATOID FACTOR — antiglobulinovy antibodies against various antigenic sites of immunoglobulin G.
R.'s activity f. it is presented in three main classes of immunoglobulins: IgM, IgG, IgA, and also can be connected with a monomeric form (7 S) IgM (see. Immunoglobulins ).
R.'s definition f., belonging to IgM with a sedimentation constant 19 S, has diagnostic value in clinic of internal diseases. It is an autoantibody with specific activity to Fc-fragments of IgG of the person. Usually R. f., belonging to IgM — polyclonal protein. Its detection is one of laboratory signs pseudorheumatism (see). It forms soluble forms of cell-bound immune complexes with endogenous IgG, can activate a complement and be fixed in fabrics. Monomeric R. f., belonging to IgM with a sedimentation constant 7 S, comes to light most often at limfoproliferativny diseases.
Diagnostic value and R.'s specificity f., belonging to IgG, are definitely not defined, but it interacts with antigenic sites of IgG, to-rye collapse at digestion by pepsin. River f., belonging to IgG, forms bonds between the separate molecules IgG that leads to formation of the immuno-complex material capable to be fixed in fabrics and to participate, apparently, in development of the damaging reactions.
Voler and Rose (E. Waaler, H. M of Rose) for the first time showed that at a pseudorheumatism in blood serum antibodies are defined, to-rye agglutinate erythrocytes of a ram, sensibilized rabbit antibodies. Then it was established that these antibodies can be revealed in an agglutination test of the particles of latex loaded with the aggregated gamma-globulin of the person. By these methods R. f is found., belonging to IgG. The specified methods are simple, are easily standardized that gives the chance to receive comparable results and found broad application at inspection of patients.
River f. comes to light at 60 — 80% of patients with a pseudorheumatism and is one of symptoms of this disease. R.'s definition f., especially in the raised credits, considerably facilitates differential diagnosis and allows to distinguish a pseudorheumatism from seronegative arthritises (see), connected with other new logical forms (rheumatism, a system lupus erythematosus, psoriasis arthritis, Bekhterev's disease, a disease of Reuters, Bekhchet's disease, a disease Krone, ulcer colitis). At a juvenile pseudorheumatism the frequency of detection of a rhematoid factor is insignificant (no more than 20%), but increases at teenagers, and its existence reflects weight of a disease in a certain measure.
R.'s definition f. at a pseudorheumatism allows to differentiate this disease on two forms: seropositive and seronegative according to R. f., what is important for forecasting of a current and the choice of treatment. Diagnostic value P. f. it is necessary to estimate in a complex with other main criteria of a pseudorheumatism.
River f. it can be found as well at other diseases — hron. diseases of a liver, tuberculosis, sarcoidosis, tropical infections. At subacute bacterial endocarditis (see) R.'s emergence f. is an adverse sign.
Bibliography: Speransky A. I. and Nasonova V. A. Problems of laboratory diagnosis in rheumatology, Owls. medical, No. 7, page 62, 1974, bibliogr.; Johnson P. M. a. Faulk W. P. Rheumatoid factor, Clin. Immunol., v. 6, p. 414, 1976, bibliogr.
A. I. Speransky.