Elevation of serum IgG subclass concentration in patients with rheumatoid arthritis

A new concept of IgG subclass such as IgG4-related systemic disease including autoimmune pancreatitis, characterized by a high-serum IgG4 level, has been proposed. Our aim was to investigate serum IgG subclass levels in rheumatoid arthritis (RA). IgG subclass levels of sera from 72 patients with rheumatoid arthritis were determined by immunonephelometric assay. The patients were divided into two groups according to clinical activity of the...