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Proc Natl Acad Sci U S A. 2005 Jun 28;102(26):9258-63. Epub 2005 Jun 20.

The evolution of human anti-double-stranded DNA autoantibodies.

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  • 1Hematopoiesis Unit, Department of Biology, Nikolaus-Fiebiger-Center for Molecular Medicine, Friedrich-Alexander University Erlangen-Nuremberg, D-91054 Erlangen, Germany.

Abstract

It has been proposed that the anti-double-stranded DNA (dsDNA) response in patients with systemic lupus erythematosus (SLE) is antigen driven and that DNA or nucleosomes select anti-DNA reactive, somatically mutated B cells. We have used site-directed mutagenesis to systematically revert the somatic mutations of two human anti-dsDNA antibodies from SLE patients to analyze the resulting changes in DNA binding as well as binding to other autoantigens. Our data demonstrate that high-affinity binding to dsDNA and nucleosomes is acquired by somatic replacement mutations in a stepwise manner. Reactivity to surface structures of apoptotic cells is acquired by the same somatic mutations that generate high-affinity dsDNA binding. Importantly, revertant antibodies with germ-line V regions did not show any measurable DNA reactivity. We propose that anti-DNA autoantibodies are generated from nonautoreactive B cells during a normal immune response. B cells may acquire autoreactivity de novo during the process of somatic hypermutation. Nucleosomes, if available in lupus patients because of defects in clearing of apoptotic debris, might subsequently positively select high affinity anti-DNA B cells.

PMID:
15968001
[PubMed - indexed for MEDLINE]
PMCID:
PMC1166593
Free PMC Article
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