The purpose of this study is to determine the safety, tolerability and preliminary efficacy of NEUK203-215 , a healthy donor (HD) allogeneic CD19/BCMA-targeted CAR-NK cell product, in participants with severe, refractory autoimmune diseases.

Inclusion Criteria:

• 1) Has provided signed informed consent; 2) Is aged 18-65 years ; 3)Adequate functional reserve of vital organs 4) Has a confirmed diagnosis of systemic lupus erythematosus, diffuse systemic sclerosis, inflammatory myopathy, or autoimmune bullous dermatosis.

Exclusion Criteria:

• 1) Requires dialysis treatment. 2) History of severe drug hypersensitivity. 3) Active infection requiring systemic therapy or suspected uncontrolled infection.

  4) Within 6 months before screening, any of the following cardiovascular events: New York Heart Association (NYHA) Class III or IV heart failure, myocardial infarction, unstable angina, uncontrolled or symptomatic atrial arrhythmia, any ventricular arrhythmia, or other clinically significant cardiac disease.

  5) Malignancy within the past 5 years. 6) Clinically significant chronic or intermittent bleeding within 60 days before the screening visit.

  7) Prior solid-organ (e.g., heart, lung, kidney, liver) or hematopoietic stem-cell/bone-marrow transplantation.

  8) At screening: positive HBsAg and/or HBcAb with HBV DNA detectable or above the lower limit of quantitation; positive HCV antibody with HCV RNA detectable or above the lower limit of quantitation; positive HIV antibody; positive syphilis test (except biologic false-positive results).

  9) Major surgery within 4 weeks before screening. 10) Live or live-attenuated vaccine received within 4 weeks before screening. 11) Uncontrolled concurrent medical conditions. 12) Documented history of neurologic or psychiatric disorders. 13) Any other factor that, in the investigator's judgment, could require premature withdrawal from the study.