The role of FcγRIIA in organ thrombosis in SLE. Representative images of hematoxylin and eosin staining for lung (A) and kidney (B) sections from B/WF1.FcγRIIA^TGN or B/WF1.FcγRIIA^Null mice at 9 and 28 weeks of age. Higher magnifications are presented in insets for each condition (scale bars are identified in upper left microscopic images in A and B and are equivalent to 50 µm). Quantification of lung thrombosis (n = 5 per group) (A) and kidney thrombosis (n = 5 per group) (B) in B/WF1.FcγRIIA^Null and B/WF1.FcγRIIA^TGN mice. Arrow heads indicate vascular thrombi, and stars indicate tubule obstruction. Data are presented as the mean ± SEM. Statistical analyses: Šídák’s multiple comparisons test (A-B). Note that in both A and B, a significant difference between 9 and 28 weeks was observed in thrombi counts only in B/WF1.FcγRIIA^TGN mice. **P < .01, ***P < .001.