CD19 and acute lymphoblastic leukemia: Increased Ktrans values in low to moderate ALL burden may indicate a therapeutic window of enhanced delivery for ALL antibody therapies, such as those targeting CD19 or CD22, which are similar in size to 150KDa dextran.39,40 However, differences in vascular transport mechanisms of dextran and therapeutic antibodies make further assessments of antibody delivery kinetics necessary.41 In contrast to 150kDa dextran, small molecular agents such as Hoechst dye and daunorubicin are able to easily cross the vessel wall of both healthy and ALL-burdened BMV.