title: Thrombocytopenia in HIV infection: impairment of platelet formation and loss correlates with increased c-Mpl and ligand thrombopoietin expression.
abstract: Thrombocytopenia is a common hematologic disorder in patients infected with the human immunodeficiency virus (HIV) and represents a risk for bleeding which is further deleterious during surgery. The major causes of the thrombocytopenia include accelerated peripheral platelet destruction by antiplatelet antibodies and insufficient production of platelets from the infected megakaryocytes. Additionally, at an earlier stage of platelet development, HIV may inhibit megakaryopoiesis at multiple stages of pluripotent CD34+ progenitor stem cell differentiation possibly contributing to decreased levels of platelets in circulation. In HIV infected patients, both the serum thrombopoietin (TPO) levels and theTPO-c-Mpl complexes on the platelet surface were significantly elevated. Therapeutic infusion of HIV infected patients with pegylated recombinant human megakaryocyte growth development factor (PEG-rHu-MGDF) restores platelet counts to normal levels and reduces the c-Mpl expression per platelet. In vitro aggregation of platelets treated with TPO and agonist, adenosine diphosphate (ADP), decrease the dose of ADP that is required for half-maximum aggregation. In vivo dosing does not effect platelet aggregation showing that the metabolism of TPO following its internalization through TPO-c-Mpl complex is rapid and that dosing within the therapeutic range does not constitute increased risk of thrombotic disease.
authors.affiliation: Laboratory of Stem Cell Biology, Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121, USA. bsundell@tpims.org
authors.forename: I Birgitta
authors.initials: IB
authors.lastname: Sundell
authors.forename: Prasad S
authors.initials: PS
authors.lastname: Koka
mesh_terms: D000328:Adult; D000818:Animals; D001792:Blood Platelets / Q000502:physiology; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D008297:Male; D002679:Pan troglodytes; D010215:Papio; D010976:Platelet Count; D011092:Polyethylene Glycols / Q000627:therapeutic use; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D018121:Receptors, Cytokine / Q000378:metabolism*; D053628:Receptors, Thrombopoietin; D011994:Recombinant Proteins / Q000627:therapeutic use; D013921:Thrombocytopenia / Q000188:drug therapy / Q000276:immunology* / Q000503:physiopathology*; D013926:Thrombopoietin / Q000378:metabolism* / Q000627:therapeutic use
chemical_list: D011518:Proto-Oncogene Proteins; D018121:Receptors, Cytokine; D053628:Receptors, Thrombopoietin; D011994:Recombinant Proteins; C103117:polyethylene glycol-recombinant human megakaryocyte growth and development factor; C082218:MPL protein, human; D011092:Polyethylene Glycols; D013926:Thrombopoietin