IFI27 and pulmonary arterial hypertension: Furthermore, based on the results of immune infiltration analysis, a significant positive correlation between ISG15 and IFI27 expression and monocytes has been observed in both HIV-1 and PAH, and it could therefore be inferred that the upregulation of ISG15 and IFI27 promotes monocyte activation and differentiation into pDCs during migration by IFN stimulation56.