Patients with pulmonary arterial hypertension will undergo cardiopulmonary exercise testing (CPET) at baseline and at 2 weeks. After the initial CPET, all patients will receive anakinra as a daily injection for 2 weeks. Patients will be instructed in the use of anakinra during their initial visit. Our primary outcome will be the difference in the exercise capacity of patients with PAH, as measured by maximal uptake of oxygen on CPET.