We performed selective and continuous immunoadsorption of anti-DNA antibodies from the blood of 6 patients with systemic lupus erythematosus, using a newly developed extracorporeal immunoadsorption system equipped with twin dextran sulfate-cellulose columns with an automated regenerating unit. Levels of anti-DNA, which were initially high, were rapidly diminished after 2-4 apheresis procedures in each patient; in 3 patients with proteinuria and 4 patients with lymphocytopenia, these symptoms also improved. Analysis of the kinetics and the adsorbed amounts of anti-DNA during the apheresis indicates that both the intravascular and the extravascular pool of anti-DNA are reduced with this potent apheresis technique.