Inclusion Criteria:

• * Male and female subjects aged between 2-30 years old. The first 3 subjects will be aged ≥ 17. The FDA will review safety data to determine if the age can be lowered first to ≥ 12 then, following the treatment of 3 further subjects aged 12-17, to ≥ 2
• * Serologically active Systemic Lupus Erythematosus that is refractory to treatment
• * Able to tolerate apheresis or already has an apheresis product available for use in manufacturing.
• * ≥ 24 weeks post last Rituximab or related B cell depleting therapy
• * ≥ 12 weeks post last Belimumab / Anifrolumab therapy
• * ≥ 4 weeks post last calcineurin inhibitor treatment
• * For subjects receiving non-calcineurin immunosuppressive therapy, on a stable dose for ≥ 8 weeks before enrollment
• * For subjects receiving corticosteroid therapy, on a stable dose for ≥ 2 weeks before enrollment
• * Adequate organ function
• * Adequate laboratory values
• * Subjects of childbearing or child-fathering potential must agree to use highly effective contraception from consent through 12 months following infusion of investigational product on trial
• * Subjects must be willing to remiain within 1 hour's drive of Seattle Children's Hospital for 4 weeks following CAR T cell infusion.
• * Subject and/or legally authorized representative has signed the informed consent form for this study

Exclusion Criteria:

• * History or presence of active CNS lupus or other CNS disease
• * Kidney dysfunction requiring renal replacement therapy
• * Pregnant or breastfeeding
• * Insufficient pulmonary reserve including history of COPD, \>10 pack year smoking history or SLE lung disease with hypoxia at rest with oxygen saturation ≤92% on room air
• * Unable to tolerate repletion with any formulation of IgG.
• * Active or prior malignancy, unless the malignancy was treated and there is no evidence of recurrent disease \<5 years from enrollment.
• * Prior solid organ transplantation.
• * Presence of an active severe infection
• * Presence of any condition that, in the opinion of the investigator, would prohibit the subject from undergoing treatment under this protocol