Dexamethasone suppresses gene expression and production of IL-13 by human mast cell line and lung mast cells.
BACKGROUND
IL-13 has been shown to induce IgE production in B cells by promoting class switching to IgE. Mast cells are known to play an important role in the pathogenesis of allergic diseases. We evaluated the ability of human mast cells to produce IL-13 using human mast cell line HMC-1 and freshly isolated lung mast cells and then examined the effect of dexamethasone on the gene expression and production of IL-13 by these cells.


METHODS
HMC-1 cells and lung mast cells were cultured with 10 ng/ml phorbol 12-myristate 13-acetate (PMA) and 1 micromol/L ionomycin and with 5 microg/ml phytohemagglutinin (PHA) and 10 ng/ml PMA, respectively, in the presence of dexamethasone. The gene expression of IL-13 at 3 hours (HMC-1 cells) or 12 hours (human lung mast cells) after stimulation was assessed semiquantitatively by sequential reverse transcription-polymerase chain reaction and Southern blot analysis. IL-13 production at 12 hours after stimulation was assayed by ELISA.


RESULTS
The gene expression of IL-13 by HMC-1 cells and human lung mast cells, which was detected at a low level in an unstimulated condition, was increased by PMA/ionomycin and suppressed by dexamethasone. The supernatant of HMC-1 cells and human lung mast cells showed a low level of IL-13, which was increased by the stimulation and suppressed by dexamethasone.


CONCLUSIONS
These findings indicate that HMC-1 cells and human lung mast cells produce IL-13 and that dexamethasone suppresses the production of IL-13 by these cells through an inhibitory action on the gene expression.
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
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T
Fushimi
H
H
Okayama
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S
Shimura
H
H
Saitoh
K
K
Shirato
D002460:Cell Line; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D018793:Interleukin-13 / Q000235:genetics*; D007700:Kinetics; D008168:Lung / Q000166:cytology; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger
D018793:Interleukin-13; D012333:RNA, Messenger; D003907:Dexamethasone