Effects of cytokine pre-treatment on IL-13 augmented calcium response to histamine. HASM were incubated with an appropriate vehicle or IFN-γ (10 ng/ml), IL-4 (5 ng/ml) or IL-13 (5 ng/ml) for 24 hours, followed by 24 hours incubation with vehicle (PBS/BSA) or IL-13. Calcium transients were measured in cells stimulated with histamine (1 μM). Data are expressed as calcium increase over baseline levels and presented as mean ± SEM of three independent experiments. *p < 0.05 compared to values obtained in cells incubated with PBS/BSA.