[Enzyme-immunoassay for autoantibodies using recombinant antigens].

The Enzyme-immunoassay (EIA) is known as safe and sensitive quantitative-method to detect autoantibodies. However, it has not been used routinely because of difficulty to prepare a large amount of native autoantigens. Many investigators have established EIA system using recombinant proteins to overcome this problem. And some of them have been useful for the diagnosis of disease and evaluation of disease activity. However, some sera positive for autoantibodies to nuclear antigens such as U1 RNP and Sm, do not react with recombinant proteins because those autoantibodies often recognize the conformational profile of the autoantigen. Therefore, using both double immunodiffusion and EIA is recommended to diagnose the patient with connective tissue disease and to evaluate the disease activities, and may clarify the clinical significance of EIA using recombinant antigens.