IGE-DEPENDENT EXPRESSION OF INTERLEUKIN-5 MESSENGER-RNA AND PROTEIN IN HUMAN LUNG - MODULATION BY DEXAMETHASONE

mRNA and protein expression of the Th2 cytokines IL-4 and IL-5 from hu man lung were examined during the first 4 hr following IgE-mediated tr iggering, a time representative of the evolving late-phase reaction (L PR). Lung explants were incubated for 16 hr at 37 degrees C in culture media alone or with added dexamethasone (10(-6) M), washed, and then challenged with buffer or anti-IgE (3 mu g/ml). Using RNase protection assays, in 16/16 individual lungs IL-5 mRNA expression was observed a t 4 hr following anti-IgE and at no points following buffer challenge, Fragments released 1129 +/- 499 ng of IL-5/g wet wt over a 24-hr peri od (mean +/- SEM, n = 5), Neither IL-4 transcripts nor protein were de tected in any anti-IgE challenges. Both the IgE-mediated IL-5 mRNA and protein responses were below the limits of detection following dexame thasone preincubation, suggesting a mechanism for the potent inhibitor y effects of these agents observed in the LPR. (C) 1995 Academic Press ,Inc.