Rheumatoid Factor Screen ELISA

INTENDED PURPOSE

Rheumatoid Factor Screen ELISA is a test system for the quantitative measurement of IgG, IgM and IgA class rheumatoid factor in human serum or plasma samples. This product is intended for professional in vitro diagnostic use only. The test is used as an aid in the differential diagnosis of rheumatoid arthritis (RA), and presence of rheumatoid factors (RF) is an integral part of the current ACR criteria for classification of RA. In established RA, high titres of serum IgG and especially IgM RF indicate poor prognosis. The presence of either IgG or IgA RF in patients with long-standing RA may be a prognostic indicator of systemic manifestations. Evaluation of a test result should always take into account all clinical and laboratory findings.

PRINCIPLE OF THE TEST

Fc fragments of highly purified human Immunoglobulin G are coated on to microwells.
The determination is based on an indirect enzyme linked immune reaction with the following steps: Specific antibodies in the patient sample bind to the antigen coated on the surface of the reaction wells. After incubation, a washing step removes unbound and unspecifically bound serum or plasma components. Subsequently added enzyme conjugate binds to the immobilized antibody-antigen- complexes. After incubation, a second washing step removes unbound enzyme conjugate. After addition of substrate solution the bound enzyme conjugate hydrolyses the substrate forming a blue coloured product. Addition of an acid stops the reaction generating a yellow end-product. The intensity of the yellow colour correlates with the concentration of the antibody-antigen-complex and can be measured photometrically at 450 nm.