Anti-CD19 CAR-NK Cells in Refractory/Relapsed Systemic Lupus Erythematosus

Inclusion Criteria: * Voluntarily participate in this clinical study, sign an informed consent form, have good compliance, and cooperate with follow-up; * Age range from 18 to 65 years old, regardless of gender; * Fulfilling the 2019 ACR/EULAR classification criteria of SLE; * Presence of anti-dsDNA or decreased C3/C4 levels; * SLEDAI-2K≥8； * Routine treatment is ineffective or the disease relapses after remission. Definition of routine treatment: use more than two drugs, including glucocorticoid (more than 1mg/kg/d), and any two or more of the following immunomodulatory drugs for more than 6 months: cyclophosphamide, mycophenolate mofetil, azathioprine, methotrexate, leflunomide, tacrolimus, ciclosporin, iguratimod, biological agents, including rituximab, belizumab, or telitacicept； * Hemoglobin ≥ 80g/L; white blood cell count ≥ 3 × 10\^9/L；neutrophil count ≥ 1.5 × 10\^9/L; platelets ≥ 30 × 10\^9/L; * The functions of important organs are basically normal: ALT ≤ 2 × ULN; AST ≤ 2 × ULN; eGFR ≥ 30ml/min/1.73m2; total bilirubin ≤2.0 mg/dL; cardiac function: left ventricular ejection fraction (LVEF) ≥ 50%; non-oxygenated blood oxygen saturation \>94%; prothrombin time (PT) ≤ 1.5 × ULN；international standardized ratio (INR) ≤ 1.5 × ULN； * Females of childbearing potential must use effective contraception during the study. Exclusion Criteria: * History of severe allergy or known hypersensitivity to any of the active ingredients of the cell product； * Pregnant (or lactating) wom…