Figure 2.

Size of FcɛRI receptor fluorescence heterogeneities on different surfaces, measured by the FWHM of the rotationally averaged intensity autocorrelation. Fluorescence heterogeneities may arise from clustering of receptors, or from variations in the proximity of the cell membrane to the substrate. The size of heterogeneities is independent of the presence/absence of ligand or the ligand mobility. Three pipette-pressed cells were analyzed for each surface. Error bars are the standard deviation. The vertical solid gray line shows the measured size of 100 nm fluorescent beads and the vertical black line is the size of the theoretical point spread function (Airy function) with effective NA = 1.33 and a wavelength of 550 nm.