Fig 2. Summary of experimental results.

(A) The contact region of a spreading neutrophil was imaged using reflection interference contrast microscopy (RICM). Contact regions in this example are traced in yellow. The scale bar in the first image denotes 10 μm. (B) Contact area is plotted as a function of time for the spreading cell shown in (A). The spreading speed is defined as the maximum slope extracted from a sigmoidal fit, and the maximum contact area is given by averaging the contact area at the plateau. (C) Mean contact area was computed at discrete time values for aligned curves of cells spreading on different densities of IgG. Mean quantified IgG densities are reported in the figure legend as IgG molecules per μm². Error bars represent standard error of the mean. (D) Average spreading speed was quantified for the different IgG densities. There is no significant difference between mean slope values. (E) Maximum contact area increases slightly as a function of IgG density. Statistically significant differences in maximum contact area values were verified using ANOVA followed by a Tukey post hoc test. Error bars in both (D) and (E) indicate standard deviation. The IgG density was quantified for each condition as described in [24].