IL-7 enhances ɛ transcripts expression. PBMCs were either unstimulated or stimulated with IL-7 and/or IL-4 for 10 days. RNA was isolated and used for Northern blot analysis using probes complementary to Cɛ (upper panel). As control, probes specific for actin were used (lower panel). In parallel, IgE was quantified in the day-10 supernatants.