Storage Instruction:Store the kit at 4°C. Description:
Rheumatoid Factors which have been found among the IgM, IgG and IgA classes of immunoglobulins, reacting only with xenogeneic Fc are not autoantibodies and are unlikely to be of pathological significance. However, RFs can bind IgG from many species, including autologous IgG, when immobilized on surfaces. Autologous binding is of higher affinity than xenogeneic binding. The here presented test systems for the deter-mination of rheumatoid factors uses only human Fc-fragments as coated antigen.
It is generally considered that high titer RFs are associated with more severe disease and the presence of extra-articular features and rheumatoid nodules. This conclusion may depend on the disease duration. Serum IgM RF may precede the onset of RA by several years. A high titer of RF in non-RA individuals is associated with increased risk of developing RA. In the first 2 years of RA (early RA), serum levels of IgM, IgG and IgA RF do not correlate with disease activity. Serum IgG and IgA RF in these years are prognostic of erosive joint disease.