Rheumatoid factor: primary or secondary event in the pathogenesis of RA?

Rheumatoid factors have been recognised and studied for over fifty years. They are anti-IgG immunoglobulins which occur in most patients with rheumatoid arthritis. Their precise contribution to the pathology of this disease however remains an enigma, since they are also demonstrable in other autoimmune and infectious diseases, as well as in normal healthy controls. Thus the importance of RF in RA may not pertain merely to their presence, but to the nature of the autoantibodies themselves. RF in RA are found to differ from those in control subjects and in other diseases such Waldenstrom's macroglobulinaemia in terms of their binding affinities for IgG, subclass specificity and V gene usage. The role of RF as either the initiating factor or its occurrence as a secondary event in RA is discussed.