RecruitingPhase 1Genetic interventionA Study of Healthy Donor CD19-targeted Allogeneic CAR T Cells in Participants With Severe, Refractory Autoimmune DiseasesThe purpose of this study is to determine the safety, tolerability, optimal dose, and preliminary efficacy of BMS-986515, a healthy donor (HD) allogeneic CD19-targeted CART cell product, in participants with severe, refractory autoimmune diseases.