By tracking the temporal evolution of CAR-T phenotypes, we demonstrated that proliferating cytotoxic-like CD8 clones were the main effectors in autoimmunity, whereas compromised cytotoxic and proliferation signature and profound mitochondrial dysfunction in CD8+ Te cells before infusion and subsequently defect CAR-T cells after manufacture might explain their characteristics in these patients. The gene discussed is CD8A; the disease is Autoimmunity.