Inclusion Criteria for Autologous Apheresis:

          -  Age ≤ 21 years old

          -  CD19+ ALL with any of the following:

               -  Minimal Residual Disease (MRD) ≥ 1% at end of up-front induction therapy

               -  Hypodiploid (< 44 chromosomes or < 0.95 DNA index) CD19+ ALL with detectable
                  disease at the end of up-front induction therapy

               -  Increase in disease burden any time after the completion of up-front induction
                  therapy

               -  Primary refractory disease despite at least 2 cycles of an intensive chemotherapy
                  regimen designed to induce remission

               -  Refractory disease despite salvage therapy

               -  1st or greater relapse

          -  Estimated life expectancy of > 12 weeks

          -  Karnofsky or Lansky (age-dependent) performance score ≥ 50

          -  Patients with a history of prior allogeneic hematopoietic cell transplantation [HCT]
             must be clinically recovered from prior HCT therapy, have no evidence of active GVHD
             and have not received a donor lymphocyte infusion (DLI) within the 28 days prior to
             apheresis

          -  For females of child bearing age:

               -  Not lactating with intent to breastfeed

               -  Not pregnant with negative serum pregnancy test within 7 days prior to enrollment

        Exclusion Criteria for Autologous Apheresis:

          -  Known primary immunodeficiency

          -  History of HIV infection

          -  Severe intercurrent bacterial, viral or fungal infection

          -  History of hypersensitivity reactions to murine protein-containing products

        Eligibility Criteria for Manufacturing SJCAR19:

          -  CD19+ ALL with any of the following:

               -  Primary refractory disease despite at least 2 cycles of an intensive chemotherapy
                  regimen designed to induce remission

               -  Refractory disease despite salvage therapy

               -  2nd or greater relapse

               -  Any relapse after allogeneic hematopoietic cell transplantation

               -  1st relapse if patient requires an allogeneic HCT as part of standard of care
                  relapse therapy, but is found to be ineligible and/or unsuitable for HCT

          -  Age: ≤ 21 years of age

          -  Karnofsky or Lansky (age-dependent) performance score ≥ 50

          -  Estimated life expectancy of > 12 weeks

          -  Meets eligibility criteria to undergo autologous apheresis, or have previously
             undergone autologous apheresis

        Inclusion Criteria for Treatment with SJCAR19:

          -  CD19+ ALL with any of the following:

               -  Primary refractory disease despite at least 2 cycles of an intensive chemotherapy
                  regimen designed to induce remission

               -  Refractory disease despite salvage therapy

               -  2nd or greater relapse

               -  Any relapse after allogeneic hematopoietic cell transplantation

               -  1st relapse if patient requires an allogeneic HCT as part of standard of care
                  relapse therapy, but is found to be ineligible and/or unsuitable for HCT for any
                  of the following reasons:

                    -  Patients that do not have an available allogeneic donor (defined as at least
                       a 7/8 HLA-matched related/unrelated donor, 5/6 HLA-matched umbilical cord
                       donor, or 3/6 HLA-matched haploidentical donor)

                    -  Patients with refractory leukemia, for which allogeneic transplant is known
                       to be less effective in the B-ALL population, and

                    -  Patients who are unable to receive myeloablative total body irradiation
                       (TBI), which is included in standard transplant regimens for patients with B
                       - ALL.

          -  Detectable disease

          -  Age: ≤ 21 years of age

          -  Estimated life expectancy of > 8 weeks

          -  Prior to planned SJCAR19 infusion, patients with a history of prior allogeneic HCT
             must be at least 3 months from HCT, have no evidence of active GVHD and have not
             received a donor lymphocyte infusion (DLI) within the 28 days prior to planned
             infusion

          -  Adequate cardiac function defined as left ventricular ejection fraction > 40%, or
             shortening fraction ≥ 25%

          -  EKG without evidence of clinically significant arrhythmia

          -  Adequate renal function defined as creatinine clearance or radioisotope GFR ≥50
             ml/min/1.73m2 (GFR ≥40 ml/min/1.73m2 if < 2 years of age)

          -  Adequate pulmonary function defined as forced vital capacity (FVC) ≥ 50% of predicted
             value; or pulse oximetry ≥ 92% on room air if patient is unable to perform pulmonary
             function testing

          -  Karnofsky or Lansky (age-dependent) performance score ≥ 50

          -  Total Bilirubin ≤ 3 times the upper limit of normal for age, except in subjects with
             Gilbert's syndrome

          -  Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≤ 5 times the upper
             limit of normal for age

          -  Hemoglobin > 8 g/dl (can be transfused)

          -  Platelet count > 20,000/μL (can be transfused)

          -  Has recovered from all NCI CTAE grade III-IV, non-hematologic acute toxicities from
             prior therapy

          -  For females of child bearing age:

               -  Not lactating with intent to breastfeed

               -  Not pregnant with negative serum pregnancy test within 7 days prior to enrollment

               -  If sexually active, agreement to use birth control until 6 months after T-cell
                  infusion. Male partners should use a condom

          -  Available SJCAR19 product with ≥ 15% expression of the CD19-CAR, and killing of CD19+
             targets ≥ 20% in an in vitro cytotoxicity assay

          -  Agreement to participate in long-term follow-up on protocol NCT00695279

        Exclusion Criteria for Treatment with SJCAR19:

          -  CNS-3 disease with or without neurologic changes

          -  CNS-1/CNS-2 disease with neurologic changes

          -  Known primary immunodeficiency

          -  History of HIV infection

          -  Evidence of active, uncontrolled neurologic disease

          -  Severe, uncontrolled bacterial, viral or fungal infection

          -  History of hypersensitivity reactions to murine protein-containing products

          -  Receiving systemic steroids therapy exceeding the equivalent of 0.5 mg/ kg/day of
             methylprednisolone, in the 7 days prior to CAR T-cell infusion

          -  Receiving systemic immunosuppressive therapy in the 14 days prior to CAR T-cell
             infusion

          -  Receiving intrathecal chemotherapy in the 7 days prior to CAR T-cell infusion