Objective To explore the risk factors of pulmonary artery hypertension (PAH) and the its relationship with T cell subsets to provide a foundation for the prevention and treatment of PAH.Methods 154 maintained hemodialysis (MHD) patients in our dialysis center were recruited according to the criterion and divided into two groups subsequently:PAH group (pulmonary artery systolic pressure,PASP ＞ 35 mmHg) and non-PAH group (PASP≤35 mmHg).The related clinical,biochemical and ultrasonic cardiogram data were collected and peripheral blood was acquired to detect the expressions of the surface antigen CD3,CD4,CD8 and CD69 with flow cytometry.Logistic regression analysis was used to find out the relationship between PAH and T cell subsets.Results There was no significant difference between 56 cases of PAH and 98 cases of non-PAH as regards gender,age,mean systolic and diastolic pressure,dialysis durations,morbidities of hypertension and diabetes,smoking rate,and left ventricular diameter.Compared with the non-PAH group,the PAH group demonstrated a lower percent of CD8 T cells and CD8 CD69 T cells,but a much higher left atrial diameter (LAD),Interventricular septum thickness,left ventricular posterior wall thickness,and NT-proBNP.The percentage of T cells,CD4 T cells and CD4 CD69 T cells showed no difference between the two groups.Multivariate analysis confirmed that PAH was negatively independently associated with the percentage of CD8 T cells and CD8CD69 T cells.Conclusions The decreased percentage of CD8 T cells and CD8CD69 T cells in the peripheral blood is a risk factor of PAH in maintained hemodialysis patients,and CD8 T cells may play an important role in the genesis of PAH.