Specific activation of FcγRI is required for its reorganization into concentric rings and segregation from SIRPα nanoclusters. (A and B) TIRF (bars, 10 µm) and dSTORM (bars, 5 µm) images showing FcγRI (green) and SIRPα (red) at the surface of human macrophages incubated for 10 (A) or 30 min (B) on slides coated with hIgG1 or hIgG2 and stained with anti–FcγRI-AF488 and anti–SIRPα-AF647 mAbs. In each condition, regions outlined by the white squares (middle column) are shown enlarged (right column) with relative fluorescence intensity profiles along the white lines. Bars, 1 µm. (C) CBC histograms of the single-molecule distributions of the colocalization parameter for FcγRI and SIRPα in cells seeded onto hIgG1- or hIgG2-coated slides for 10 (light gray and dark gray, respectively) or 30 min (light red and dark red, respectively). Data are from a minimum of 30 cells from three independent donors. Bars represent mean ± SD. (D) NND analysis from data shown in C. Each symbol represents the median NND of all paired single-molecule localizations from one cell. Horizontal lines and error bars represent mean ± SD. ns, not significant; **, P < 0.01; ****, P < 0.0001; one-way ANOVA with Tukey’s post-hoc test. (E) Histogram distributions of the NND between the centroids of nanoclusters from one channel and the centroid of their nearest neighbor from the second channel (≥20,000 clusters from a minimum of 10 cells per condition). a.u., arbitrary units; NN, nearest neighbor; PC, positive control.