Stimulation of HPASMC with TNFα resulted in a significant (p < 0.01) induction of IL-8 mRNA at 2 h which continued to increase to around 8 h where levels were some 6000 times higher than basal levels in control cells and 700 times higher in PAH HPASMC. This evidence concerns the gene CXCL8 and pulmonary arterial hypertension.