title: Direct binding of monomeric anti-DNA antibodies to Raji cells.
abstract: The Raji-cell test is one of the most widely used methods for the detection and quantitation of immune complexes. Immune complexes and not 7 S IgG bind via C3 to complement receptors on the cell membrane of the Raji cell. During sucrose gradient fractionation of human and murine systemic lupus erythematosus sera, with a high Raji cell-binding activity, we could not demonstrate immune complexes in these sera. Subsequent analysis showed that the major part of the Raji cell binding was used by 7 S IgG with an anti-DNA specificity. Blocking experiments with complement-bearing aggregated IgG revealed that complement and Fc receptors were not involved in the binding of these anti-DNA antibodies to Raji cells. We conclude that the Raji cell test is not suitable for the detection and quantitation of immune complexes in sera containing anti-DNA antibodies.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000378:metabolism*; D000936:Antigen-Antibody Complex / Q000032:analysis*; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D046911:Macromolecular Substances; D051379:Mice; D011951:Receptors, Complement / Q000378:metabolism; D011961:Receptors, Fc / Q000378:metabolism; D017452:Receptors, IgG
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D046911:Macromolecular Substances; D011951:Receptors, Complement; D011961:Receptors, Fc; D017452:Receptors, IgG; D004247:DNA