Mast Cells Play a Critical Role in the Pathogenesis of Viral Myocarditis

Background— Mast cells are powerful producers of multiple cytokines and chemical mediators playing a pivotal role in the pathogenesis of various cardiovascular diseases. We examined the role of mast cells in murine models of heart failure due to viral myocarditis, using 2 strains of mast cell–deficient mice. Methods and Results— Two strains of mast cell–deficient mice, WBB6F1-KitW/KitW-v (W/WV) and WCB6F1-KitlSl/KitlSl-d (Sl/Sld), were inoculated with 10 plaque-forming units of the encephalomyocarditis virus intraperitoneally. On day 14 after inoculation, survival of W/WV mice was significantly higher than that of their control littermates (77% versus 31%; P=0.03; n=13). On histological examination on day 7, myocardial necrosis and cellular infiltration were significantly less pronounced in W/WV and Sl/Sld mice than in their control littermates (area of infiltration, 7.6±3.5% versus 29.3±15.6%; P=0.002; area of necrosis, 7.6±3.5% versus 30.0±17.2%; P=0.003; n=10). Histological examination showed more seve...