Animal models deficient in cytotoxic t lymphocyte-associated protein-4 (CTLA-4) and programmed cell death protein-1 (PD-1), show T lymphocyte infiltration and severe myocarditis with a rise in cardiac biomarkers, such as troponin and cardiomyocyte necrosis, on pathology. This evidence concerns the gene PDCD1 and myocarditis.