This clinical trial is designed as a single - arm, open - label, single - center, investigator - initiated early - phase clinical study. The primary objective is to evaluate the safety of UTAA91 injection in treating subjects with relapsed/refractory autoimmune inflammatory diseases (AID).

Following the signing of the informed consent form, eligible subjects will receive an infusion of UTAA91 injection. Blood samples will be collected from the subjects before and after the infusion for pharmacokinetic, pharmacodynamic, immunogenicity, and safety assessments.

Aside from the baseline period, efficacy evaluations will be conducted periodically during the treatment phase after cell reinfusion until the occurrence of one of the following events, with the earliest event taking precedence: disease progression, initiation of new anti - disease treatment, death, intolerable toxicity, the investigator's decision, or the subject's voluntary withdrawal.

Inclusion Criteria

1. Age ≥ 18 years (including the cut - off value), with no restrictions on gender.
2. Expected survival time ≥ 3 months.
3. Subjects with relapsed/refractory autoimmune diseases who have failed standard treatment or lack effective treatment options, including but not limited to rheumatoid arthritis, systemic sclerosis, systemic lupus erythematosus, idiopathic inflammatory myopathies, Sjögren's syndrome, connective tissue disease - related interstitial lung disease, immune thrombocytopenia, primary biliary cholangitis, etc.
4. Liver and kidney functions and cardiopulmonary functions meet the requirements.
5. No severe mental disorders.
6. Able to understand this trial and have signed the informed consent form.

Exclusion Criteria

1. Malignant tumors other than relapsed/refractory autoimmune diseases (R/R AID) within 5 years before screening.
2. Subjects with positive virus and/or syphilis tests.
3. Presence of severe heart disease or unstable systemic diseases.

5. Presence of active or uncontrollable infections requiring systemic treatment.

6. Pregnant or breastfeeding women, as well as female subjects who plan to become pregnant within 2 years after cell infusion or male subjects whose partners plan to become pregnant within 2 years after their cell infusion.

7. Subjects who have received CAR - T therapy or other gene - modified cell therapies before screening.