This pilot study seeks to examine the feasibility and safety of administering T cell antigen presenting cells (T-APCs) designed to reactivate and numerically expand CD19-specific CAR T cells. The underlying hypothesis to be examined is that after remission is achieved with CAR T cell treatment, the duration, magnitude, and activation state of persisting memory CAR T cells impact on the potential for durable leukemia eradication. This is of particular relevance in several groups of patients we have identified: those who are predicted to lose persistence of their CAR T cells before Day 63, or those who have definitively lost persistence of CAR T cells prior to 6 months. By providing these patients with episodic exposure to T-APCs capable of activating CD19-specific CAR T cells for proliferation and redistribution to tissue beds where tumor cells of ALL seed, ideally over several months following remission induction, it is posited that the incidence of disease relapse will be diminished.