Time course of IL-6, histamine, and serotonin secretion. WT and α2-null (KO) FSMCs (5 × 104/well) were treated overnight with either Listeria plus antibody and serum (LAS) (a-c) or anti-DNP IgE followed by stimulation with DNP-HSA (IgE + DNP) (d-f) for the indicated time points. Cell-free supernatants were collected and analyzed for IL-6 (a, d), histamine (b, e), or serotonin (c, f). Data are presented as means ± SEM and are representative of at least 3 similar experiments.