Combined defect in membrane expression and activation of platelet GPIIb-IIIa complex without primary sequence abnormalities in myeloproliferative disease

• Published in: British journal of haematology 2000-12, Vol.111 (3), p.954-964
• Main Authors: KAPLAN, Robert, GABBETA, Jagadeesh, LING SUN, GUANG FEN MAO, RAO, A. Koneti
• Format: Article
• Language: English
• Subjects: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid - pharmacology; Adenosine Diphosphate - pharmacology; Aged; Antibodies, Monoclonal - metabolism; Binding Sites; Biological and medical sciences; Blood Platelets - metabolism; Calcimycin - pharmacology; Diglycerides - pharmacology; DNA, Complementary - genetics; Enzyme Activators - pharmacology; Flow Cytometry; Hematologic and hematopoietic diseases; Hematology; Humans; Immunoblotting; Ionophores - pharmacology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Macrophage-1 Antigen - analysis; Male; Medical sciences; Myeloproliferative Disorders - blood; Myeloproliferative Disorders - immunology; Neutrophils - immunology; Peptides - pharmacology; Platelet Activating Factor - pharmacology; Platelet Aggregation; Platelet Aggregation Inhibitors - pharmacology; Platelet Glycoprotein GPIIb-IIIa Complex - analysis; Platelet Glycoprotein GPIIb-IIIa Complex - metabolism; Polymerase Chain Reaction; Protein Binding; Protein Kinase C - metabolism; Receptors, Thrombin - metabolism; RNA, Messenger - analysis; Sequence Analysis, DNA; Serotonin - secretion; Signal Transduction
• ISSN: 0007-1048; 1365-2141
• DOI: 10.1046/j.1365-2141.2000.02444.x

Defects in glycoprotein (GP)IIb-IIIa or in its activation may cause abnormal platelet aggregation and a bleeding diathesis. We report studies in a 67-year-old man with a myeloproliferative disease and markedly abnormal platelet responses. By flow cytometry, platelet binding of two complex-specific anti-GPIIb-IIIa monoclonal antibodies (mAbs), A2A9 and 10E5, was approximately 50% of normal. An enzyme-linked immunosorbent assay (ELISA) using immobilized kistrin showed 18% of normal membrane GPIIb-IIIa complex. By immunoblot analysis, GPIIb and GPIIIa levels in platelet lysates and membranes were near normal. Activation of GPIIb-IIIa, monitored with mAb PAC-1, was markedly decreased (< 20% of normal) in response to ADP, thrombin and platelet-activating factor (PAF); expression of ligand-induced binding sites (LIBS) was < or = 30% of normal. Signal transduction-independent LIBS expression, induced by echistatin, was approximately 60% of normal, suggesting that the integrin present had intact ligand-binding capability. Sequence analysis of GPIIb and GPIIIa cDNA, and platelet mRNA levels for both subunits, were normal. These findings document an acquired combined defect in membrane expression (secondary to a defect in post-translational processing of the complex) and inside-out signalling-dependent activation of the GPIIb-IIIa complex.