CD19 and acute lymphoblastic leukemia: We classified AL into five review categories according to the affected cell lineage: Pro B-ALL (CD34+ CD19+ cyCD79a+), Pro B–Pre B-ALL (CD34−/+ CD19+ cyCD79a+), Pre B-ALL (CD34− CD19+ cyCD79a+), TALL (cyCD3+ smCD3lo CD7+), and AML (cyMPO+ or CD7+).