Suppression of gene expression and production of interleukin 13 by dexamethasone in human peripheral blood mononuclear cells.

We examined the effect of dexamethasone on the gene expression and production of interleukin (IL)-13 by human peripheral blood mononuclear cells from healthy controls. The gene expression was assessed semiquantitatively by sequential transcription polymerase chain reaction and Southern blot analysis, and the production of this cytokine was assessed by enzyme-linked immunosorbent assay (ELISA). Dexamethasone suppressed IL-13 gene expression induced by stimulation with phytohemagglutinin and phorbol 12-myristate 13-acetate in a dose-dependent manner, with 96% suppression at 10−6 M, and also suppressed the increased production of IL-13. This is suggested to be one of the mechanisms by which glucocorticoids suppress allergic inflammation.