IVIg and IV.3 provide partial and full protection, respectively, from platelet destruction in vivo. (A) Study timeline of animal experiment. The VITT condition was recreated in FcγRIIa⁺/hPF4⁺ transgenic mice by the administration of VITT IgG. Anticoagulants, IVIg and IV.3 were administered via an osmotic pump and/or IV injection, as described in “Methods.” Platelet counts were assessed in mice after treatment with (B) anticoagulants (argatroban, bivalirudin, danaparoid, or UF heparin), (C) IVIg, and (D) aglycosylated IV.3. Data are shown as mean ± SD. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001, relative to VITT IgG. nIgG, normal IgG.