IL-9 induces BCL3 expression. The indicated IL-9–responsive cells were cultured in medium containing saturating concentrations of the indicated cytokines: 10 days in the presence of 100 U/mL IL-2, 200 U/mL IL-4, or 200 U/mL IL-9 for T-helper cell clones (TS2, TS3, and ST2K9) and 10 days in the presence of 200 U/mL IL-3 or 200 U/mL IL-9 for mast cell lines (L138 and MC9). BMMC were cultured in the presence of 20 U/mL IL-3 or a combination of IL-3 and IL-9 (200 U/mL). The mouse lymphoma line BW5147 was stimulated for 2 days with 500 U/mL IL-9 or IL-4 or 10,000 U/mL IL-6. After electrophoresis of 10 μg of total RNA and transfer to nitrocellulose, filters were hybridized with a 32P-labeled mouse BCL3 cDNA probe. Hybridization with a β-actin probe confirmed that comparable amounts of RNA had been loaded in each lane.
