Agly-IV.3 and recombinant effector-deficient CD32a mAbs inhibit M90 IC-induced thrombocytopenia and thrombosis. (A) Bar charts showing the percentage of platelets remaining in circulation of FCGR2A mice following the injection of M90 ICs. Three hours prior to IC challenge mice were pretreated with PBS or CD32a mAbs (as in Figure 4A-E) or with aspirin, bivalirudin, or eptifibatide. (B) Mean number of clots in the lung vasculature of animals pretreated as in panel A, obtained by counting intravascular clots in 5 fields per 3-μm section (mean + SD). The data in panels A and B represent the same animals. An all pairwise multiple comparison using the same Holm-Sidak 1-way ANOVA procedure for each data set (A-B) showed a difference between treatment groups (P < .001), and that each effector-deficient mAb (columns 2-6) differed significantly (P < .001) from PBS (column 1). (C) Representative H&E lung section (×200) of control mouse (from PBS group shown in panel B). Arrowheads identify occlusive intravascular thrombi. (D) Representative H&E lung section (×200) from cAT-10 IgG1 E269R pretreated FCGR2A mouse (from panel B) followed by anti-CD40L IC injection showing blood vessels containing erythrocytes (red) but lacking thrombi.