Flow cytometric analysis of data of one representative patient. a-c; gating of a representative experiment. Black regions and arrows indicate gating strategy. The PBS control is in blue, and the optimal allergen concentration (0,1 μg/ml) is in red. Histograms of expression of CD63 at visit 2 (d). Data smoothed by R for CD63 were used to determine LC50, the allergen concentration at which half-maximal activation (LC50) is achieved (e) LC50 was normalised to baseline and plotted against visit number.