Terminal Transferase-Positive Human Bone Marrow Cells Exhibit the Antigenic Phenotype of Common Acute Lymphoblastic Leukemia

Abstract

Combined immunologic assays for TdT enzyme and membrane markers show that TdT⁺ cells in nonleukemic human bone marrow carry ALL-associated and Ia-like antigens but no thymocyte markers or surface Ig. These cells could be precursors involved in acute lymphoblastic leukemia of the “common” or non-T, non-B type and in lymphoid blast crisis of Ph' positive chronic myeloid leukemia. A few TdT⁺, Ia⁺ cells express cytoplasmic IgM, indicating that some pre-B cells may be TdT positive.