Lactoferrin interacts with deoxyribonucleic acid: a preferential reactivity with double-stranded DNA and dissociation...

LF was found to bind to deoxyribonucleic acid as assessed by immunofluorescence studies on cell nuclei, affinity chromatography of DNA on immobilized LF, and gel chromatography of an LF-DNA reaction mixture. LF immobilized on Sepharose 4-B was reacted with 125I-labeled DNA in both its double-stranded and single-stranded configurations; dsDNA eluted with a 0.69M NaCl buffer, whereas ssDNA eluted with a 0.25M NaCl buffer. Additional evidence for a preferential reactivity with dsDNA was provided by the enzymatic treatment of preformed dsDNA-LF and ssDNA-LF complexes with S1 endonuclease, and DNAse 1--DNase digestion alone liberated free LF. The interaction of LF with DNA partially inhibited the binding of anti-DNA antibodies from patients with SLE, as assayed in a standard Farr assay. Furthermore, DNA-anti-DNA (labeled with 125I-IgG) complexes could be dispersed in vitro by the addition of LF. It is hypothesized that the release of LF by neutrophils chemotactically attracted to DNA-anti-DNA complexes may act as a feedback loop to modulate the inflammatory response in SLE.