CD19 CAR-T Cells for Patients With Relapse and Refractory CD19+ B-ALL.

Inclusion Criteria: 1. More than 1 year; 2. CD19 positive B-cell acute lymphoblastic leukemia; 3. Important organ function is satisfied: cardiac ultrasound indicates cardiac ejection fraction ≥50%, no obvious abnormality in ECG; blood oxygen saturation ≥90%; creatinine clearance calculated by Cockcroft-Gault formula ≥40ml/min; ALT and AST≤ 5 times normal range, total bilirubin ≤ 34.2 μmol / L. 4. Expected to survive for more than 3 months; 5. Informed consent is signed by a subject or his lineal relation. Exclusion Criteria: 1. Recent or current use of glucocorticoid or other immunosuppressor; 2. Uncontrolled active infection, HIV infection, syphilis serology reaction positive; 3. Has a graft-versus-host response and requires the use of immunosuppressants； 4. Drug uncontrollable central nervous system leukemia； 5. Pregnant or lactating female； 6. The patient did not agree to use effective contraception during the treatment period and for the following 1 year； 7. A history of other malignant tumors; 8. The investigator believes that there are other factors that are not suitable for inclusion or influence the subject's participation or completion of the study.