Figure 6

Mast cell activation: tyrosine phosphorylation, calcium signals, degranulation. A. Analysis of overall protein phosphorylation on tyrosine residues. Upper panel; overall tyrosine-phosphorylation pattern was analysed in cell extracts from: control unstimulated cells (Basal); cells treated with IgE alone for (IgE) for 5 min; and after FcεRI crosllinking for 5 min (XLFcεRI). Lower panel; the blots were probed for α-tubulin (control for equal loading). Results shown are representative of four separate experiments. B. Levels of intracellular free calcium. Intracellular calcium measurements of mast cells following addition of IgE alone (IgE); and following the addition of the anti-human IgE, to IgE-sensitized cells (XLFcεRI), the intracellular calcium levels were analyzed in a continuous reading for the timesstated in the graph. Results shown are the mean plus the standard deviation of triplicate measurements and are representative of four separate experiments. C. Degranulation. B-hexosaminidase release was determined from control-unstimulated mast cells (Basal); following monomeric-IgE-sensitization for 30 minutes (IgE); and following FcεRI aggregation by addition of the anti-human IgE to sensitized cells for 30 minutes (XLFcεRI). Results shown are the mean plus the standard deviation of triplicate measurements and are representative of four separate experiments.