Cardiac myosin–induced experimental autoimmune myocarditis in IFN-γ–KO mice developed pericarditis leading to a constrictive phenotype. The pericardium in KO mice was thickened with white discoloration causing adhesions between the two pericardial layers and to the pleura, diaphragm, and chest wall. This evidence concerns the gene IFNG and autoimmune myocarditis.