Anti-endothelial cell autoantibodies (AECA), anti-endothelin-1 type A receptor (ETAR) autoantibody, anti-angiotensin II type I receptor (AT1R) autoantibody, γ/δ T cells, cytotoxic CD4+ T cells (CD4+ CTLs), and natural killer (NK) cells are involved in EC activation and damage in SSc [17]. Here, CD4 is linked to systemic sclerosis.