ARG1 and myocarditis: Beyond specific immune cell-type markers, peri-granuloma stroma exhibits increased expression of class I and II MHC molecules (Beta-2-microglobulin and HLAD-DR) – a phenomenon known to occur in association with myocardial inflammation.31–35 Peri-granuloma stroma also exhibits increased expression of inflammation-associated pro-fibrotic mediators such as arginase 1,36,37, fibronectin,38 and CD4439,40.