[Dot immunobinding assay in detection of IgE-type rheumatoid factor]

The sera from 86 patients with autoimmune diseases, 31 atopic and 65 healthy blood donors were detected for IgE type rheumatoid factor (IgE-RF) by using anti-human IgE monoclonal antibody and dot immunobinding assay. The positive frequency and mean value of IgE-RF in patients with autoimmune diseases were significantly higher than those in the other groups. IgE-RF was positive in 19/37 cases of rheumatoid arthritis (RA), 6/18 systemic lupus erythematosus and 13/31 primary Sjogren's syndrome, with mean values of 23.1, 12.1 and 26.9 ng/ml respectively. 75% RA patients with IgM-RF (+) had IgE-RF, with a mean value of 27.0 ng/ml, whereas 33% of those with IgM-RF (-) had IgE-RF with a mean value of 16.5 ng/ml. In contrast, only 2/31 atopic and 6/65 healthy blood donors had positive IgE-RF with mean values of 3.7 and 6.1 ng/ml respectively. Hence, IgE-RF is helpful not only in raising the sensitivity of RA diagnosis, but also in distinguishing autoimmune diseases from allergy.