To assess the in vitro cytotoxicity of CAR T-cells derived from SLE, IIM, and SSc patients and HDs, CAR T-cells and non-transduced T-cells were co-cultured with autologous primary B-cells, CD19+ NALM-6 B-cells, or CD19− U937 non-B-cells at E:T ratios of 1:1 and 3:1 for 16 h. The gene discussed is CD19; the disease is systemic lupus erythematosus.