We compared the different immune functions in IPAH and normal controls and found that most immune functions, including Th1_cells, Tfh, T_helper_cells, T_cell_co-stimulation, T_cell_co-inhibition, pDCs MHC_class_I, Inflammation-promoting, Cytolytic_activity, Check point, CD8+_T_cells, Macrophages down, and CCR, were significantly enriched in IPAH compared with normal samples. The gene discussed is CD8A; the disease is idiopathic pulmonary arterial hypertension.