Model of acute and chronic anti-GPIbα antibody–induced platelet clearance. High-dose anti-GPIbα mAb injection opsonizes platelets, leading to platelet activation and aggregation, followed by a rapid clearance from the circulation by liver macrophages and hepatocytes via the AMR (ie, acute antibody-mediated platelet clearance). Hepatic platelet clearance induces rapid thrombopoietin (TPO) production. In contrast, low-dose subcutaneous injections lead to a gradual decrease in circulating platelet count (ie, mimicking chronic thrombocytopenia). After low-dose mAb, platelet clearance is only observed in the spleen by macrophages, and TPO levels remain unaltered. Illustration by Leonardo Rivadeneyra, Versiti Translational Glycomics Center.