Figure 1.
Platelet aggregation and trapped neutrophils in response to immune complexes in FcγRIIATGN mice. (A) The number of platelet aggregates observed in response to immune complexes or diluent in both FcγRIIAnull mice (dark blue) and FcγRIIATGN mice (pink) (n = 5-6 mice for each condition). (B) Mean platelet aggregate area in response to immune complexes or diluent in both FcγRIIAnull mice (dark blue) and FcγRIIATGN mice (pink) (n = 5-6 mice for each condition). (C) Mean number of platelet aggregates containing at least 1 neutrophil in both FcγRIIAnull mice (dark blue) and FcγRIIATGN mice (pink) (n = 5-6 mice for each condition). ND, statistical test not defined because of the absence of platelet aggregates in 1 of the groups of mice. (D) Mean number of neutrophils inside platelet aggregates in both FcγRIIAnull mice (dark blue) and FcγRIIATGN mice (pink) (n = 5-6 mice for each condition). ND, statistical test not defined because of the absence of platelet aggregates in 1 of the groups of mice. (E) Schematic representation of thrombotic events observed with a high-speed widefield fluorescence microscope in the brain of FcγRIIATGN mice injected intravenously with immune complexes. (F) Absence of platelet aggregates in FcγRIIATGN::Ly6gCre+/−::Rosa26-TdT+/−::CD41-YFP+/− mice injected with diluent (n = 6 mice). (G) Formation of platelet aggregates (cyan) in FcγRIIATGN::Ly6gCre+/−::Rosa26-TdT+/−::CD41-YFP+/− mice injected with immune complexes leads to obstruction of blood vessels (n = 6 mice). (H) Schematic representation of neutrophils trapped in platelet aggregates observed in the brain of FcγRIIATGN mice injected intravenously with immune complexes. (I) Platelets (cyan) and neutrophils (red) circulating in the brain of FcγRIIATGN::Ly6gCre+/−::Rosa26-TdT+/−::CD41-YFP+/− mice injected with diluent. (J) Platelet aggregates (cyan) can trap neutrophils (red, yellow arrows) (n = 5 mice of 6). Bars show mean ± SEM. Two-way ANOVA with repeated measures followed by a post-hoc Holm-Bonferroni test (A-B). *P < .05; **P < .01; ***P ≤ .001. Bars represent 50 µm. The direction of blood flow is indicated with double white arrowheads. Time following the injection of immune complexes is indicated in the inferior right corner (00:00 = minutes:seconds).