Dexamethasone inhibits IL-9 production by human T cells.
BACKGROUND
Interleukin 9 (IL-9) is produced by activated CD4+ T cells. Its effects include stimulation of mucus production, enhanced mast cell proliferation, enhanced eosinophil function, and IgE production. These effects are consistent with a role in allergic diseases. Glucocorticoids have potent anti-inflammatory effects, including suppression of cytokine synthesis, and are widely used in the treatment of allergic conditions.


METHODS
We examined the effect of the glucocorticoid dexamethasone (Dex) on IL-9 mRNA expression and protein secretion with real-time RT-PCR and ELISA. Peripheral blood mononuclear cells (PBMC) were prepared from human volunteers and activated with OKT3. CD4+ T cells were purified from PBMC and activated with OKT3 plus PMA.


RESULTS
IL-9 mRNA abundance and protein secretion were both markedly reduced following treatment of activated PBMC with Dex. mRNA levels were reduced to 0.7% of control values and protein secretion was reduced to 2.8% of controls. In CD4+ T cells, Dex reduced protein secretion to a similar extent. The IC50value of Dex on mRNA expression was 4 nM.


CONCLUSIONS
These results indicate that IL-9 production is very markedly inhibited by Dex. The findings raise the possibility that the beneficial effects of glucocorticoids in the treatment of allergic diseases are in part mediated by inhibition of IL-9 production.
Holz
Lauren E
LE
Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia.|Centre for Immunology, St. Vincent's Hospital, University of NSW, NSW 2052, Australia.
Jakobsen
Kristoffer P
KP
Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia.
Van Snick
Jacques
J
Ludwig Institute of Cancer Research, Brussels Branch and the Experimental Medicine Unit, Universite de Louvain, B-1200 Brussels, Belgium.
Cormont
Francoise
F
Ludwig Institute of Cancer Research, Brussels Branch and the Experimental Medicine Unit, Universite de Louvain, B-1200 Brussels, Belgium.
Sewell
William A
WA
Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW 2010, Australia.|Centre for Immunology, St. Vincent's Hospital, University of NSW, NSW 2052, Australia.|St Vincent's Clinical School, University of NSW, NSW 2052, Australia.