Which of the following statements about Rheumatoid Factor is true -
It is an IgM antibody directed against IgG
It is an IgG antibody directed against IgM
It is more specific than Anti-CCP antibodies
It is positive in all cases of Juvenile Rheumatoid Arthritis
Rheumatoid factor in Rheumatoid Arthritis is an IgM antibody directed against the Fc fragment of IgG
Anti CCP antibodies are most specific blood test for rheumatoid arthritis (specificity ∼ 95%).
Rheumatoid factor is positive in only 10% of patients with JRA.