Figure 3
Interleukin (IL)-4 drives mast cell activation, growth, and survival, and the IL-4Rα immunoreceptor tyrosine-based inhibitory motif limits these effects. (a) Il4rαF709 bone marrow mast cells (BMMC) exhibit enhanced phosphorylation of STAT6 (signal transducer and activator of transcription factor 6) in response to IL-4 stimulation. (b) Immunoglobulin E receptor (FcɛRIα) upregulation by IL-4 is enhanced in Il4rαF709 BMMC at 24 h. (c) IL-4 (2 ng ml−1), but not IL-13 (10 ng ml−1), enhances mast cell growth in combination with IL-3 and stem cell factor (SCF), particularly for Il4rαF709 BMMC. (d) Mast cell death in the absence of IL-3 and SCF is prevented by IL-4 but not IL-13, and the effect is more evident in Il4rαF709 BMMC. (e) IL-4 induces greater Bcl-2 and Bcl-XL expression in Il4rαF709 than wild-type BMMC. Statistical analysis by two-way analysis of variance ANOVA).*P<0.05, **P<0.01, and ***P<0.0001 by Bonferroni post-test where indicated. Data are representative of at least three experiments. MFI, mean fluorescent intensity.
