CD4 and cardiac hypertrophy: Using lymphocyte deficient RAG2-deficeint mice, T-cell-deficient TCRα–/– mice, CD4+ T-cell-selective depleted mice, CD8+ T-cell-selective depleted mice, and T-cell co-stimulation blocker abatacept, studies showed that cardiac CD4+ T cells contribute to cardiac hypertrophy by promoting cardiac tissue fibrosis and inflammation (Laroumanie et al., 2014; Nevers et al., 2015; Kallikourdis et al., 2017).