Interplay between GPIb/IX antibodies, platelet hepatic sequestration, and TPO levels in patients with chronic and nonsplenectomized ITP with severe thrombocytopenia.¹Association found between GPIb/IX antibody levels and increased hepatic sequestration of platelets. ²Association found between hepatic sequestration and increased TPO levels. ³Direct association between GPIb/IX antibody levels and increased TPO levels.