Cross-reactive binding patterns of monoclonal antibodies to DNA are often caused by DNA/anti-DNA immune complexes.
Recently, the role of antibodies to DNA in the pathogenesis of systemic lupus erythematosus (SLE) has been reevaluated, since observed cross-reactive binding of anti-DNA to tissue-related antigens might substantially contribute to the inflammatory process of the disease. Evidence of this cross-reactivity has, in part, been obtained from studies with monoclonal anti-DNA. However, we now report that the presence of DNA/anti-DNA immune complexes in monoclonal antibody preparations may be the cause of the observed cross-reactive binding patterns. Studying a panel of anti-DNA producing hybridomas (n = 63), we detected such immune complexes in 76% of the obtained culture supernatants by using an anti-protamine sulphate (PS) ELISA; complexes formed with 1 microgram/ml DNA or more were traced in this assay. In cultures of anti-DNA-producing hybridomas, complexes were detected from day 3 on. Treatment of supernatants with DNase reduced the anti-PS reactivity to an average of only 20% of the original reactivity. Contaminating DNA/anti-DNA immune complexes were found to play no role in the cross-reactivity of anti-DNA antibodies with cardiolipin, a minor role in cross-reactivity with dextran sulphate, but a substantial role in the cross-reactivity with heparan sulphate, histones and other nuclear or cytoplasmic antigens. Our results clearly demonstrate that exclusion of the presence of immune complexes in antibody preparations is a prerequisite when cross-reactivity patterns of anti-DNA antibodies are studied.
Central Laboratory, the Netherlands Red Cross Blood Transfusion Service, Amsterdam.
K
K
Brinkman
R M
RM
Termaat
J
J
de Jong
H G
HG
van den Brink
J H
JH
Berden
R J
RJ
Smeenk
D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex / Q000032:analysis; D002846:Chromatography, Affinity; D003429:Cross Reactions; D004247:DNA / Q000276:immunology*; D003851:Deoxyribonucleases; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D015151:Immunoblotting; D008180:Lupus Erythematosus, Systemic / Q000209:etiology / Q000276:immunology; D051379:Mice
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D004247:DNA; D003851:Deoxyribonucleases