IFN-λ1 regulates the expression of GATA3 and T-bet. (A) Purified naive CD4⁺ T cells and memory T cells were cultured under Th2 (anti-CD2/3/28 beads + 10 ng/mL IL-4) or control conditions (10 ng/mL IL-4), in the presence (■) or absence (□) of IFN-λ1. Total RNA was harvested after 18 hours, and expressions of GATA3 and T-bet were measured by real-time PCR. Graphs show expression levels (fold change) of cells stimulated under Th2 conditions, normalized to unstimulated cells under control conditions. (B) Purified naive CD4⁺ T cells were harvested, and protein was extracted and probed for the presence of GATA3, which was normalized by densitometry against levels of β-actin. One representative experiment of 3 is shown.