Immunology of DNA. VI. The effect of mercaptans on IgG and IgM anti-dsDNA.
Reduction of IgM antibodies to DNA with mercaptans such as dithioerythrol or 2-mercaptoethanol completely destroys DNA binding in the Farr assay and in the immunofluorescence technique by Crithidia luciliae. In contrast reduction of IgG antibodies to DNA results in a six-fold increase of DNA binding in the Farr assay while no effect on titres in the immunofluorescence technique can be observed. Our results lead to the following conclusions: 1) The Farr assay is selective for high avidity interactions; only a minor part of IgG antibodies to DNA is measured; 2) 7S IgM antibodies to DNA cannot be demonstrated in the Farr assay or the immunofluorescence technique; obviously only multivalent interactions, as obtained with the intact 19S IgM molecule are stable in these assays; 3) reduction of IgG leads to a greater flexibility of this molecule; this facilitates monogamous bivalent binding to DNA; 4) THE PRESENTATION OF DNA in the kinetoplast of Crithidia luciliae favours a monogamous bivalent binding of antibodies to DNA with high avidity; this accounts for occasionally observed discrepancies between anti-DNA activity in the Farr assay and in the immunofluorescence technique.
D000906:Antibodies; D000917:Antibody Formation; D001666:Binding Sites, Antibody; D004247:DNA / Q000276:immunology*; D004226:Dithioerythritol / Q000494:pharmacology*; D004229:Dithiothreitol / Q000031:analogs & derivatives*; D056890:Eukaryota / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism*; D007158:Immunologic Techniques; D008623:Mercaptoethanol / Q000494:pharmacology*; D010396:Penicillamine / Q000494:pharmacology
D000906:Antibodies; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008623:Mercaptoethanol; D004226:Dithioerythritol; D004247:DNA; D010396:Penicillamine; D004229:Dithiothreitol