The role of α-acidic glycoprotein in formation of bleeding abnormalities in patients with myeloproliferative neoplasms

Abstract

Aim: To compare glycoforms of alpha-acid glycoprotein (AGP) in myeloproliferative neoplasms (MPN) with hepatic lesions. Materials and Methods: 110 patients with MPN (31 with polycythaemia vera (PV), 75 with primary myelofibrosis (PMF), 4 with essential thrombocythemia (ET)) were examined. 92 patients with atherosclerotic lesions of lower extremities and 10 healthy people comprised the control. AGP concentration in blood serum was determined by rocket electrophoresis and affinity chromatography. The carbohydrate moiety of AGP was studied by lectin blotting with panel comprising eight lectins. The total content of sialic acids and the type of chemical linkage with galactose were determined. Results: High-molecular fragments of AGP detected in MPN (MM 68, 84, and 126 kDa) have been shown as deriving from leukocytes with glycan moiety identified as neutrophilic component. In MPN with thrombotic complications, AGP fragments with MM 84 and 126 kDa prevailed with hypersialic components suggesting the leukocyte component (originated from polymorphonuclear neutrophils) as the principal element in the development of thrombotic complications. Furthermore, in MPN with thrombotic complications, strong direct correlation was established between high levels of lactate dehydrogenase (LDH) and C-reactive protein on the one hand and high-molecular fragments of AGP with MM 84 and 126 kDa on the other hand. AGP level depended on primary diagnosis: in PV AGP level decreased, PMF (leukocytosis > 20 G/l) was characterized by normal level of AGP due to neutrophilic component. In MPN, glycosylation of AGP was reduced due to the N-glycans. Increase in the amount of branched glycans and sialylation of AGP in MPN seemed to originate from the high activity of neutrophils. Conclusion: It is determined that the deficiency of platelets and leucocytes function plays an important role in progression of myeloproliferative syndrome with myelofibrosis formation. Key Words: α-acidic glycoprotein, myeloproliferative neoplasms, polymorphonuclear neutrophils, thrombohemorrhagic complications.