Umbilical Cord Blood CD19-BCMA CART Cell Therapy for SLE-LN, SSc, andpSS PAH.

This study is testing CAR-T cell therapy made from umbilical cord blood — rather than the patient's own cells — for people with severe autoimmune diseases (lupus nephritis, systemic sclerosis, or Sjögren's-related pulmonary arterial hypertension) that haven't responded to other treatments. **You may be eligible if...** - You are between 3 and 65 years old - You have refractory lupus nephritis confirmed by biopsy showing active, proliferative disease (type III or IV) - OR you have systemic sclerosis or Sjögren's-related pulmonary hypertension that hasn't responded to standard treatment - Your disease was confirmed within the last 6 months by biopsy or other criteria - You have failed multiple standard immunosuppressive treatments **You may NOT be eligible if...** - Your condition does not meet the specific diagnostic criteria - You have active, serious infections - Your organ function is too impaired to receive cell therapy safely - You have received certain prior immune or cell therapies Talk to your doctor to see if this trial is right for you.