Rheumatoid factor

Rheumatoid factor (RF) is an autoantibody that targets denatured IgG and is species-specific. RF-producing B cell clones are present in rheumatoid arthritis (RA) patients and in approximately 50% of healthy individuals, and can be synthesized in large quantities under certain pathological factors such as denaturing IgG or Epstein-Barr virus. RF binds poorly to native IgG but is susceptible to reaction with IgG or polymeric IgG in immune complexes. It has been confirmed that the CH2 functional region of the heavy chain of the IgG molecule is rich in an oligosaccharide formed by the cross-linking of asparagine, which is said to be an antigen-binding epitope reactive with RF. There are five types of RF, IgG, IgA, IgM, IgD, and IgE. The detection of RF is important for the diagnosis, classification and therapeutic effect of rheumatoid arthritis (RA). There are many methods for detecting RF. Latex agglutination test and ELISA method are commonly used, and the latex method mainly measures IgM type RF. The ELISA method can be used to determine RF in different Ig categories, and it can also achieve quantitative detection, which is more practical. Basic Information Specialist classification: examination classification: blood examination Applicable gender: whether men and women apply fasting: fasting Tips: Light diet and control sorghum diet such as animal viscera spinach. Normal value Normal human serum RF titer <1:20 (latex agglutination test). IgG-RF < 186 U/ml, IgA-RF < 261 U/ml, IgM-RF < 226 U/ml (indirect ELISA). The total RF threshold (double antigen sandwich ELISA) can also be derived from a survey of the normal population. Clinical significance Abnormal results: (1) When the high-frequency RF in the serum of RA patients is accompanied by severe joint function limitation, the prognosis is often indicated. The RF positive rate of untreated RA patients is about 80%, the latex method titer is often above 1:160, and about 1% to 4% of normal people are weakly positive. (2) Among all types of Ig, IgG-RF is closely related to synovitis, vasculitis and arthritis symptoms in RA patients; IgA-RF is found in RA, scleroderma, Felty syndrome and SLE, which is clinically active in RA. One index, IgD-RF studies are rare; IgE-RF is also seen in Felty syndrome and young RA in addition to RA patients; IgM-RF levels are not closely related to RA activity. (3) In non-RA patients, the positive rate of RF increases with age, but these people have few RA afterwards. Need to check the population suspected of having rheumatoid arthritis. Positive results may be disease: Kaplan syndrome, synovitis, hemorrhoids, impetigo, bone hypertrophy, osteomyelitis, nodular erythema Inappropriate people: generally no special population. Taboo before the test: light diet and control sorghum diet such as animal viscera spinach. Requirements for examination: Sometimes the lumps will be a little stiff and painful! So pay attention to the doctor when checking. Inspection process 1. Inactivated at 56 ° C for 30 minutes (inactivate C1q to prevent false positive agglutination). The serum to be tested was diluted 1:20 with 0.1 mol/LPH 8.2 glycine buffered saline (0.05 ml of serum was added to 1 ml of physiological saline). 2. Take 1 drop of this diluted serum (about 0.05ml), add it to the square of the black square glass slide, add 1 drop of latex RF reagent, shake the reaction plate for 3 minutes, mix it fully, and shoot it in direct light. Under observation. Positive and negative controls were set up for each test. Not suitable for the crowd There are no special taboos. Adverse reactions and risks There are no related complications and hazards.

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