CMA1 and triple-A syndrome: Mast cells promote AAA expansion by releasing cytokines (IL6, interferon‐γ [IFN‐γ]) and proteases (chymase, tryptase) to activate vascular and inflammatory cells.[7, 8, 9, 10] In contrast, EOS slow AAA growth by releasing IL4 and cationic proteins to block matrix degradation, angiogenesis, and vascular and inflammatory cell activation, and promoting SMC proliferation and M2 macrophage and Ly6Clo monocyte polarization.[11]