Rheumatoid factor RF IgG

Rheumatoid factor RF IgG

Clinical significance

Rheumatoid factor is an antiglobulin antibody directed against human and animal immunoglobulin G epitopes. The most common, 80%, is the classic RF factor (RF IgM), detected in 1949 by Waaler and Rose. In addition, rheumatoid factors can belong to immunoglobulin class G or A, less commonly D or E. Rheumatoid factor is a major serological marker in the diagnosis of rheumatoid arthritis (85%) and in patients with other connective tissue diseases (syndrome Sjögren, systemic lupus erythematosus, systemic scleroderma, mixed connective tissue disease and others). In low titers, it is also detected in about 3-5% of healthy people especiallyóld after the age of 60. In the course of the disease, in addition to the stimulation of the immune system and the formation of immune complexes, RF is involved in the activation of complement. RF in combination with immune complexes intensifies inflammatory processes leading to cartilage destruction and joint destruction, as well as to the development of extra-articular form of rzs (cardiovascular, respiratory, ocular, renal lesions, rheumatoid nodules). The seropositive form of rzs is usually characterized by a more severe course of the disease. The presence of RF IgG may be associated with the occurrence of vasculitis in the rzs, while RF IgA is considered a marker of the erosive form and increased bone erosive changes. Determination of RF in immunoglobulin classes other than IgM is only of ancillary importance. Rheumatoid factor levels also fluctuate depending on the active disease process, which is useful in monitoring the course of the disease and the effectiveness of treatment. RF is routinely determined by classical Waaler-Rose and latex reagents (qualitative result) or by immunoturbidimetry, nephelometry or ELISA methods (quantitative result). Rheumatoid factor can be determined in serum, as well as in joint fluid and effusion fluids.

Patient preparation

no special recommendations

Material: Serum

Interventions

severe hemolysis, lipemia - triglycerides over 2000 mg/dl, bilirubin over 40 mg/dl