RESUMO
@#【Objective】To investigate the expression and clinical significance of programmed death- 1（PD- 1），programmed death-ligand 1（PD-L1）and CD4+ CD25+ Foxp3+ regulatory T cells（Treg）and CD4+/CD8+ ratios in JAK2V617F mutation positive myeloroliferative neoplasms patients（MPN）.【Methods】45 cases of JAK2 V617F positive MPN patients were selected including 17 cases of essential thrombocythemia（ET），13 cases of polycythemia vera（PV）and 15 cases of primary myelofibrosis（ET）. 30 cases of the newly diagnosed group and 15 cases of treatment group were from them. 15 cases of healthy volunteers were selected as control group. The ratio of mutant and wild type of JAK2 was detected by fluorescence quantitative polymerase chain reaction（FQ-PCR）. The expression levels of p-JAK2，PD-1 and PD- L1 in pathological tissues of bone marrow were detected by immunohistochemistry. The changes of treg cells and lymphocyte subsets in peripheral blood of MPN patients and controls were detected by flow cytometry. 【Results】 The expression levels of p-JAK2，PD-1，PD-L1，and Treg in the newly diagnosed group were significantly higher than that of treatment group and control group（P<0.05），while the expression levels of CD4 +/CD8 + ratio were significantly lower than treatment group and control group（P<0.05）. JAK2 V617F mutation burden was positive correlation with PD-1 and PD- L1，and was negative correlation with CD4 +/CD8 + ，the correlation coefficients were r=0.593，P<0.01；r=0.723，P<0.01；r=-0.771，P<0.01，respectively.【Conclusion】p-JAK2，PD-1，PD-L1，Treg，CD4+/CD8+ and JAK2 V617F were involved in the pathogenesis of myeloroliferative neoplasms.