MCs were sensitized overnight with anti-DNP IgE then placed on a layer of pericytes (stained with CMTMR) and stimulated with increasing concentrations of DNP-BSA for 24 hours. (A) Schematic depicting the coculture experiment between primary mouse lung MCs and pericytes. (B) Images of unstimulated or stimulated (100 ng/ml DNP-BSA) pericyte/MC cocultures stained for DAPI (yellow), CMTMR (purple), PDGFRβ (blue), and avidin (green, MC granules). White boxes indicate the areas zoomed in showing examples of resting or degranulated MCs. Scale bars: 15 μm. Representative of 3 independent experiments. (C) Frequency of degranulated MCs. n = 6–8 images from 3 independent experiments. (D) Number of pericytes per field of view. n = 15 images from 3 independent experiments. (E) Pericyte volume determined using the cell tracer CMTMR. n = 253–299 pericytes from 3 independent experiments. (F) Avidin signal on small pericytes (<17,000 μm³) and large pericytes (>45,000 μm³) showing that small pericytes exhibit more MC granule staining on their surfaces. n = 18–46 from 3 independent experiments. (G) Representative images of F-actin (green) and N-cadherin (magenta) pericyte expression in the presence of degranulated MCs or control. Scale bars: 50 μm. Representative of 3 independent experiments. (H–I) F-actin (H, n = 98–144) and surface N-cadherin (I, n = 98–144) MFI on pericytes. Three independent experiments. Data are represented as means ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001, 1-way ANOVA followed by Tukey’s post hoc test (C, D, E, H, and I); 2-tailed Student’s t test (F).