25-hydroxycholesterol: Gatekeeper of intestinal IgA

High levels of cholesterol and diets high in fat are associated with immune dysfunction and inflammatory disease. In this issue of Immunity, Trindade et al. (2021) report how the cholesterol metabolite 25-hydroxycholesterol restrains IgA plasma cell differentiation from germinal-center B cells in the Peyer's patches through regulation of the sterol-sensing transcription factor SREBP2, independently of EBI2-mediated migration.