Platelet glycoprotein IIIa gene expression in normal and malignant megakaryopoiesis.

The platelet glycoprotein GPIIb/IIIa functions as a receptor for fibrinogen in platelet aggregation process and is an example of an early megakaryocytic marker. One of a chronic myeloproliferative disorder, essential thrombocythemia, is caused by abnormal megakaryopoiesis. Due to the lack of reliable method for the diagnosis of that disease and the importance of GPIIIa as a marker for identifying early megakaryocytes, the expression level of GPIIIa in mononuclear and CD34(+) cells and during megakaryopoiesis was compared between normal individuals and patients with essential thrombocythemia. For this purpose, surface markers GPIIIa and CD34 were analyzed with flow cytometer, and GPIIIa expression level was measured with real-time polymerase chain reaction (PCR) method. Mononuclear and CD34(+) cells from normal individuals and patients were isolated, analyzed, and seeded into serum-free medium Stemspantrade mark Medium enriched with IL-6, IL-3, thrombopoietin, and stem cell factor. The difference between normal individuals and patients was noticed in the expression level of GPIIIa in the CD34(+) cells and in the time course of cell surface markers. CD34(+) cells from patients has 33% higher of GPIIIa antigens on the surface and 34% higher GPIIIa messenger RNA (mRNA) expression level. The negative effect of IL-3 on the maturation of megakaryocytes was not noticed; there were 56.46% of megakaryoblasts at the end of the cultivation, and after 14 days of culturing, 111.09 times increase of GPIIIa mRNA in patients was detected. This study is therefore offering the method that could serve as reliable tool for discriminating ET from other similar myeloproliferative disorders.