IL25 and aortitis: Il1rn−/− mice transferred with Il25−/−Il1rn−/− BM cells developed aortitis similarly to Il1rn−/− mice transferred with Il1rn−/− BM cells (Fig. 7a), indicating that IL-25 produced by BM cell–derived immune cells was not essential for development of aortitis in Il1rn−/− mice.