CD4 and myocarditis: Even if the clear pathogenetic mechanisms are not fully understood, this review has clearly described the double-edged sword role of CD4+ cells in both initiating and mediating recovery in myocarditis; this dual role could be due to TNF-α signaling, which promotes myocarditis development by activating cardiac endothelial cells to recruit T cells, but it can also trigger the activation-induced cell death pathway in cardiac-reactive T cells [129].