CD4 and leukemia: Ex vivoshRNA-TGF-β1-EVs promote maturation of DCs via ↓ TGF-β1 expression.DC/shRNA-TGF-β1-EVs more efficiently promoted:1) CD4+ T cell proliferation;2) Th1 cytokine secretion;3) Efficient antileukemia CTL response;as compared with DC/EVs.In vivoL1210 leukemia modelVaccination (SC) of mice with DC/shRNA-TGF-β1-EVs in both prophylactic and therapeutic settings resulted in more significant inhibition of tumour growth in comparison with DC/EVs.