CD4 and myocarditis: Interestingly, both CD4 regulatory T cells and CD39 may be positively correlated with the risk of developing myocarditis, and it can be hypothesized that overexpression or aberrant activation of CD39 and CD4 regulatory T cells leads to a weakening of their inhibitory effects, causing abnormalities in the immune system, which then exacerbates immune responses, including inflammatory responses, in cardiomyocytes.