Dominant Role for Regulatory T Cells in Protecting Females Against Pulmonary Hypertension.

Rationale: Pulmonary arterial hypertension (PH) is a life-threatening condition associated with immune dysregulation and abnormal regulatory T cell (Treg) activity, but it is currently unknown whether and how abnormal Treg function differentially affects males and females.

Objective: To evaluate whether and how Treg deficiency differentially affects male and female rats in experimental PH.

Methods And Results: Male and female athymic rats, lacking Tregs, were treated with the VEGFR2 (vascular endothelial growth factor receptor 2) inhibitor SU5416 or chronic hypoxia and evaluated for PH; some animals underwent Treg immune reconstitution before SU5416 administration.