CpG motif-containing DNA fragments from sera of patients with systemic lupus erythematosus proliferate mononuclear cells in vitro.
OBJECTIVE
To characterize DNA in sera of patients with systemic lupus erythematosus (SLE) in terms of size, guanine plus cytosine (G+C) content (by percentage), CpG dinucleotide (CpG) (percentage), and effects on mononuclear cells (MNC).


METHODS
Nine DNA clones were sequenced. Oligodeoxynucleotides with the characteristic CpG motif (TTCGAA or PuPuCGPyPy) were examined for their proliferative effect on MNC by [3H]thymidine incorporation, expression of HLA-DR and intercellular adhesion molecule (ICAM)-1 on monocytes by flow cytometry, and mRNA levels encoding interleukin 12 (IL-12) and interferon-gamma (IFN-gamma) by semiquantitative reverse transcription polymerase chain reaction.


RESULTS
The size of DNA clones ranged from 87 to 318 bp (mean +/- SD, 177+/-68) and enrichment in G+C and CpG ranged from 34.7 to 69.7% (48.1+/-10.7) and 0.63 to 12.8% (4.0+/-4.1), respectively. Three of 9 clones contained the characteristic CpG motif. Oligonucleotides proliferated MNC, and augmented HLA-DR and ICAM-1 expression in company with an increase of mRNA encoding IL-12 and IFN-gamma.


CONCLUSIONS
Circulating CpG motif-containing DNA fragments in SLE increased mRNA encoding IL-12 and IFN-gamma, which in turn increased HLA-DR and ICAM-1 on monocytes, resulting in MNC proliferation. This mechanism could contribute to the pathogenesis of SLE.
Sato
Y
Y
Fukushima Medical University School of Medicine, Fukushima-city, Japan.
Miyata
M
M
Sato
Y
Y
Nishimaki
T
T
Kochi
H
H
Kasukawa
R
R
D001483:Base Sequence; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D018899:CpG Islands / Q000235:genetics / Q000502:physiology*; D004247:DNA / Q000737:chemistry* / Q000502:physiology; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism; D006684:HLA-DR Antigens / Q000097:blood; D006801:Humans; D066298:In Vitro Techniques; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood; D007371:Interferon-gamma / Q000235:genetics; D018664:Interleukin-12 / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000166:cytology* / Q000187:drug effects*; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects / Q000235:genetics; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012333:RNA, Messenger / Q000097:blood; D020133:Reverse Transcriptase Polymerase Chain Reaction