Apolipoprotein AI prevents regulatory to follicular helper T cell switching during atherosclerosis.

Regulatory T (Treg) cells contribute to the anti-inflammatory response during atherogenesis. Here we show that during atherogenesis Treg cells lose Foxp3 expression and their immunosuppressive function, leading to the conversion of a fraction of these cells into T follicular helper (Tfh) cells. We show that Tfh cells are pro-atherogenic and that their depletion reduces atherosclerosis.