Our results showed that CD8+ T cells, CD4+ memory resting T cells, γ delta T cells, M1 macrophages, and resting mast cells were upregulated, while CD4+ naive T cells, resting NK cells, monocytes, M0 macrophages, activated mast cells, and neutrophils were downregulated in IPAH samples. The gene discussed is CD4; the disease is idiopathic pulmonary arterial hypertension.