CD4 and pulmonary arterial hypertension: In addition, immune cell infiltration analysis showed that activated CD4 T cells, regulatory T cells, and type 2 T helper cells were upregulated in m7G cluster B, CD56 dim natural killer cells, MDSC, and monocyte were upregulated in the m7G cluster A. It might be helpful to select Calpain inhibitor I and Everolimus for the treatment of PAH.