CpG oligodeoxynucleotide prolongs eosinophil survival through activation of contaminating B cells and plasmacytoid dendritic cells in vitro.
BACKGROUND
In our previous study, oligodeoxynucleotides containing unmethylated CpG motifs (CpG ODNs) significantly prolonged eosinophil survival without inducing active release of eosinophil-derived neurotoxin or interleukin 8. In addition, this survival-promoting activity was nuclear factor-kappaB dependent. However, some eosinophil preparations from different donors hardly responded to CpG ODNs at all. To clarify why CpG ODN-induced nuclear factor-kB activation in eosinophils does not cause eosinophil-derived neurotoxin or interleukin 8 release and why the survival-promoting activity of CpG ODNs was not found in some eosinophil preparations, we determined the effect of extensive removal of contaminating B cells and plasmacytoid dendritic cells from human eosinophil preparations.


METHODS
Eosinophils were purified from the peripheral blood of healthy or slightly allergic donors by gradient sedimentation and negative selection with anti-CD16 alone or a combination of anti-CD16, anti-CD19 and anti-blood dendritic cell antigen 4 (BDCA4) immunomagnetic beads. Eosinophil survival was measured with FITC-conjugated annexin V and propidium iodide by FACS after incubation with synthetic CpG 2006(CpG-B), CpG 2216 (CpG-A) or their GpC control ODNs for 24 h.


RESULTS
The addition of anti-CD19 and anti-BDCA4 immunomagnetic beads reduced the number of contaminating CD19+ cells and CD123+ BDCA2+ cells in eosinophil preparations. CpG 2006 and CpG 2216, but not their GpC control ODNs, significantly prolonged survival of eosinophils purified with anti-CD16 immunomagnetic beads alone but not eosinophils purified with a combination of anti-CD16, anti-CD19 and anti-BDCA4 beads.


CONCLUSIONS
These results strongly suggest that contaminating B cells or plasmacytoid dendritic cells in eosinophil preparations critically regulate CpG ODN-mediated prolongation of eosinophil survival and that CpG ODNs do not activate eosinophils directly.
Matsumoto
Kenji
K
Department of Allergy and Immunology, National Research Institute for Child Health and Development, Tokyo, Japan. kmatsumoto@nch.go.jp
Terakawa
Maki
M
Fukuda
Shuhei
S
Kato
Atsushi
A
Toki
Shinji
S
Shinohara
Miwa
M
Wakiguchi
Hiroshi
H
Saito
Hirohisa
H
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D018941:Antigens, CD19 / Q000276:immunology; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects* / Q000276:immunology; D004804:Eosinophils / Q000187:drug effects* / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D018189:Immunomagnetic Separation; D008213:Lymphocyte Activation / Q000187:drug effects* / Q000276:immunology; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D017452:Receptors, IgG / Q000276:immunology
D000276:Adjuvants, Immunologic; D018941:Antigens, CD19; C408982:CPG-oligonucleotide; D009838:Oligodeoxyribonucleotides; D017452:Receptors, IgG