Fig. 1

Characterization of peripheral blood-derived mast cells (PBdMC) and LAD2 cells. Immunofluorescence staining for tryptase in mast cells, representative staining is shown in red for tryptase (a). Transmission electron microscopy image of a mature PBdMC (b). Flow cytometry of PBdMC using antibodies against CD117: Mast cell marker (c-Kit), CD34: Progenitor cell marker, CD88: Marker for some mast cells (c5a-receptor) (c). Mast cell degranulation was measured by the ability to release β-hexosaminidase. The calcium ionophore A23187 efficiently degranulated LAD2 cells in a concentration-dependent manner, IgE/Anti IgE stimulation also triggered degranulation of LAD2 cells but at a lower level than A23187 (d). The maximum effect was observed at 0.5 μg/ml of Anti IgE. (mean ± SD, 3 individual experiments with 3 technical replicates in each experiment, *p < 0.05, **p < 0.01 and ***p < 0.001)