RecruitingPhase 2Biological interventionIVIG for Infection Prevention After CAR-T-Cell TherapyThis phase II trial compares the effects of immunoglobulin replacement therapy with a placebo for preventing infectious complications in patients receiving CD19 chimeric antigen receptor (CAR)-T cell therapy. Hypogammaglobulinemia is a common complication in patients who receive CD19 CAR-T cell therapy. This is a condition in which the level of immunoglobulins (antibodies) in the blood is low and the risk of infection is high. Immunoglobulin replacement therapy works by replacing the body's immunoglobulin G (IgG) antibodies with donor blood product derived IgG antibodies that may help prevent infection. IgG antibodies are often depleted as a result of CAR-T therapy. Giving immunoglobulin replacement therapy may prevent infectious complications in patients receiving CD19 CAR-T cell therapy.