It has been shown that cationic anti-DNA antibodies have nephritogenic potential in murine models of lupus nephritis. More recently, we have reported that there is a close relationship between the presence of circulating cationic anti-DNA antibodies and the development of lupus nephritis in humans, and that the cationic anti-DNA antibodies bind to heparan sulfate, a major glycosaminoglycan in glomerular basement membrane, much better than neutral anti-DNA antibodies. This suggests that cationic anti-DNA antibodies of the IgG class may be responsible for development of nephritisin vivoin patients with systemic lupus erythematosus. In this study, we first studied reactivity of anti-DNA antibodies with a panel of glycosaminoglycansin vitrousing ELISA methods, and found that anti-DNA antibodies cross-react with dextran sulfate, hyaluronic acid and chondroitin sulfate. The reactivity and selectivity of dextran sulfate with anti-DNA antibodies was confirmed byin vitroimmunoadsorption of the patient's sera with dextran sulfate-fixed column; incubation of auto-antibody-positive sera with dextran sulfate cellulose column removed anti-DNA, but not anti-RNP, anti-Sm, anti-SSA and anti-SSB antibodies from the serain vitro.Of note is that dextran sulfate cellulose column adsorbed exclusively, if not all, cationic anti-DNA antibodies in their sera. Nonspecific binding of total immunoglobulins as well as total proteins to the column was marginal. It has been suggested that cationic anti-DNA antibodies in sera of patients with refractory lupus nephritis could be efficiently removed by apheresis using dextran sulfate column.