Polycythemia Vera Study Of Disease Pathogenesis

Polycythemia Vera (PV) is a clonal stem cell disease with yet unknown pathogenesis. Previous works have demonstrated that there were endogenous erythroid colonies (EECs) growing in vitro from PV patients. Two suppositions have been put forward to explain the emergence of EECs. One is the Epo-hypersensitivity of early erythroid cells, and the other is the Epo-independence of the cells as recently proposed. With the understanding of the structure and function of the Epo receptor (EpoR) and EpoR encoding gene, the fact are current known that factor to evoke the action of EpoR is not necessarily Epo per se. For instance the transgenic mice with EpoR mutant (R129) could developed polycythemia. It means that a mutant of EpoR might be constitutionally in an active form and able to function by itself without the participation of its ligand Epo, But the role of EpoR in the pathogenesis of human PV is not clear.In order to define the role of genetic changes of EpoR in the development of PV, the expression of EpoR gene was examined in the erythroid progenitor of PV. The expression of EpoR gene is tissure-specific and controlled in line with cell differentiation. EpoR reaches its climax in the stage of CFU-E. We firstly established the method of gaining CFU-E from peripheral blood, by two-step liquid culture of peripheral blood mononuclear cell . In the first step, the culture medium contained IL-3 which stimulates the proliferation and diffrentiation of BFU-E, and in the second step Epo was included to ensure the differentiation of erythroid progenitors. It was proved by methycellulose semisolid colony assays that the production of CFU-E was highest on the fourth day after adding Epo, and the purity of CFU-E could reach 30% and above. The cells corresponding to CFU-E from PV patients and normal controls were collected and the expression of EpoR was detected by Northern blot. The probe was EpoR DNA which contained the 150 bp at the 5' region of EpoR gene. The result showed that there were no difference of EpoR mRNA in respect to the amount and molecular length between all 5 cases of PV patients and normal. This result seemingly suggested that the pathogenesis of PV might not be relevant to EpoR, athough much...