CD4 and precursor B-cell acute lymphoblastic leukemia: The ratio of CD4+ and CD8+ T cells is highly variable in patients with B-ALL and NHL, and studies have shown that the injection a 1:1 ratio of CD4 to CD8 CAR-T cells can ameliorate this phenomenon, resulting in predictable polyclonal proliferation of CD4 + and CD8 + T cells in patients, thereby increasing the persistence of CAR-T cells (15, 16).