is_about leukemia systemic sclerosis infectious disease systemic lupus erythematosus rheumatoid arthritis Sjogren syndrome antibody measurement rheumatoid factor measurement true NCIt:C74717 NCIt:C805 Dani Welter SNOMEDCT:54921001 quantification of rheumatoid factors, 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. https://en.wikipedia.org/wiki/Rheumatoid_factor