Rheumatoid factor (RF) is (DNB June 2009)
|A||An autoantibody directed against the Fc fragment of the IgG|
|B||An acute phase reactant|
|C||An antibody against the Fab portion of IgM|
|D||The factor responsible for DIC|
An autoantibody directed against the Fc fragment of the IgG
It is an antibody against the Fc fragment of IgG, it can be IgG, IgM; and IgA isotype but in clinical practice usually the IgM isotype is measured. RF can be measured by latex agglutination, sheep red cell agglutination, EUSA and nephelometry, of these latex agglutination is the most commonly used because of its simplicity.