What is Rheumatoid factor-from screening to personalized management.

The rheumatoid factor (RF) is a representative autoantibody against the crystallizable fragment (Fc) of denatured immunoglobulin (Ig) G that are primarily detected in patients with rheumatoid arthritis (RA). Although five types of tumor necrosis factor (TNF) inhibitors can be used to treat RA, no guidelines are available for selecting the appropriate inhibitor for treatment. High serum RF levels are associated with high disease activity, progressive joint destruction, life prognosis associated with organ damage, decreased treatment responsiveness to TNF inhibitors and other drugs, and low treatment retention rates. Meanwhile, certolizumab pegol (CZP), a TNF inhibitor without the Fc region, remains at high concentrations in the blood. Unlike other antibody drugs with the Fc region, CZP maintains efficacy in patients with high serum RF levels. When serum IgM-RF levels are high, antibody drugs with the Fc region are more likely to bind to IgM-RF and be degraded. Thus, CZP without the Fc region may be more favorable for patients with high serum RF levels.