This is a single-center, open-label, non-randomized, single-arm clinical trial. Patients with refractory lupus neritis (SLE-LN), systemic sclerosis (SSc), primary Sjogren syndrome combined with pulmonary artery hypertension (pSS-PAH) and other autoimmune diseases (AID) receive CD19-BCMA CAR T cell therapy. Phase I (Dose-Escalation/Dose-De-escalation Phase)：The primary objective is to prospectively assess the safety of CD19-BCMA CAR T cell therapy in patients with SLE-LN, SSc, pSS-PAH and other autoimmune diseases (AID).Phase I (Dose-Escalation/Dose-De-escalation Phase)：Primary Endpoint: Safety, tolerability, and determination of the optimal biological dose (OBD) and the Phase II recommended dose (RP2D) in patients with SLE-LN, SSc, pSS-PAH, and other autoimmune diseases (AID).Phase II (Dose-Expansion Phase):Overall remission rate (ORR) \[Time Frame: 90,180 Days\]
Refractory Lupus Nephritis（LN）: Patients who meet all the following requirements can be enrolled in the group.
Male or female, aged 10-65 years;
Meeting the 2019 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) Classification Criteria for Systemic Lupus Erythematosus (Appendix 4);
The ANA result is positive which means ANA titer≥ 1:80 (based on the equivalent detection results by Hep-2 immunofluorescence assay or enzyme immune assay), and/or according to the detection results from center laboratory, during the screening visit,the anti dsDNA serum antibody test is positive (based on ELISA assay, ≥30 IU/mL);
Intracranial hypertension or disorder of consciousness;
Symptomatic heart failure or severe arrhythmia;
Symptoms of severe respiratory failure;
Complicated with other types of malignant tumors;