Human lupus monoclonal autoantibodies bind to Raji cells

Seven of 60 human monoclonal anti-DNA autoantibodies derived from 3 patients with SLE were shown to bind to Raji cells by radioimmunoassay. The binding of the lupus autoantibodies to the Raji cells in solution was not affected by prior incubation of the cells with DNase. Preincubation of the monoclonal autoantibodies with polynucleotides and cardiolipin, resulted in significant inhibition which correlated with the direct binding characteristics of these antibodies. Previous results with mouse IgG monoclonal anti-DNA antibodies supported by our results with human IgM anti-DNA autoantibodies suggest caution in interpreting analyses of immune complexes of sera containing anti-DNA antibodies entailing Raji cells.