title: CpG motifs in bacterial DNA activate leukocytes through the pH-dependent generation of reactive oxygen species.
abstract: B cells and monocytes endocytose DNA into an acidified intracellular compartment. If this DNA contains unmethylated CpG dinucleotides in particular base contexts (CpG motifs), these leukocytes are rapidly activated. We now show that both B cell and monocyte-like cell line responses to DNA containing CpG motifs (CpG DNA) are sensitive to endosomal acidification inhibitors; they are completely blocked by bafilomycin A, chloroquine, and monensin. The specificity of these inhibitors is demonstrated by their failure to prevent responses to LPS, PMA, or ligation of CD40 or IgM. Acidification of endosomal CpG DNA is coupled to the rapid generation of intracellular reactive oxygen species. The CpG DNA-induced reactive oxygen species burst is linked to the degradation of IkappaB and the activation of NFkappaB, which induces leukocyte gene transcription and cytokine secretion. These studies demonstrate a novel pathway of leukocyte activation triggered by CpG motifs.
authors.affiliation: Interdisciplinary Graduate Program in Immunology and Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Yi
authors.forename: R
authors.initials: R
authors.lastname: Tuetken
authors.forename: T
authors.initials: T
authors.lastname: Redford
authors.forename: M
authors.initials: M
authors.lastname: Waldschmidt
authors.forename: J
authors.initials: J
authors.lastname: Kirsch
authors.forename: A M
authors.initials: AM
authors.lastname: Krieg
mesh_terms: D000818:Animals; D002738:Chloroquine / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004269:DNA, Bacterial / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D020672:I-kappa B Proteins; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008811:Mice, Inbred DBA; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D017382:Reactive Oxygen Species
chemical_list: D002738:Chloroquine; D016207:Cytokines; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D015226:Dinucleoside Phosphates; D020672:I-kappa B Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D017382:Reactive Oxygen Species; C083487:I kappa B beta protein; C000606205:Nfkbia protein, mouse; C015772:CpG dinucleotide