NCIt definition : Antibodies in the serum of individuals with rheumatoid arthritis that react with antigenic
determinants or immunoglobulins that enhance agglutination of suspended particles
coated with pooled human gamma-globulin. Rheumatoid factors also occur in other autoimmune
and certain infectious diseases.;
Alternative definition : NICHD: Antibodies that bind other immunoglobulins frequently seen in rheumatoid arthritis
but can be found in other autoimmune diseases.;