RF

Rheumatoid factors are a group of antibodies directed to determinants in the Fc portion of the immunoglobulin G molecule. Although rheumatoid factors are found in a number of rheumatoid disorders, such as systemic lupus erythematosus (SLE) and Sjögren's syndrome, as well as in nonrheumatic conditions, its central role in clinic lies in its utility as an aid in the diagnosis of rheumatoid arthritis (RA) . A study of the "American College of Rheumatology" shows that 80,4% of RA patients were RF positive.