Mast cells are mandatory for FcγRIIA-dependent passive cutaneous anaphylaxis. (A-C) Mice were injected intradermally with indicated reagents and intravenously with Evans blue. Quantification of Evans blue extracted from skin tissue is represented. (A-B) PCA in 5KO (open symbols: A, n = 4; B, n = 3), 5KOIIA (black symbols: A, n = 3, B, n = 3), or 5KOIIA mice preinjected (A) once or (B) twice with 50 μg mAb IV.3 (gray symbols, n = 4). (C) PCA in 3KOIIA mice (black symbols, n = 4), in W^sh3KOIIA (gray symbols, n = 3), and as controls in W^sh3KO (open symbols, n = 2). NB: 2 points are represented per mouse, as each mouse was injected on 2 different sites with Ag and with IC. (D) Representative expression of FcγRIIA on peritoneal mast cells (c-kit⁺/IgE⁺) from 3KOIIA mice (open histograms) or 3KO littermate controls (filled histograms). (E-F) Peritoneal cells from 3KO (white bars) and 3KOIIA (black bars) mice were stimulated with indicated reagents. (E) The percentage of degranulated mast cells (a minimum of 200 cells were counted per experimental point), and (F) histamine content in the supernatant of each experimental point are represented. (A-C) Data are represented as single measured points, and mean ± SEM. (A-F) Data are representative of at least 2 independent experiments (*P < .05; ***P < .001).