title: Proliferation of lymphoid precursor cells in the bone marrow of patients with various disorders of the immune system.
abstract: In the human bone marrow the nuclear enzyme terminal deoxynucleotidyl transferase (TdT) is expressed by cells during early stages of lymphocyte differentiation. In order to investigate a possible regulation of lymphopoiesis at this level of differentiation, the relative frequency and the in vitro 3H-thymidine labeling index (3HdT-LI) of TdT-positive bone marrow cells were assessed in patients with different functional activities of the immune system. TdT-positive lymphoid precursor cells could be detected in the bone marrow of all children investigated, including six patients with various forms of immunodeficiency. Neither a transient hyperfunction of the immune system during the immunological rebound after cessation of long-term chemotherapy for acute lymphoblastic leukemia, nor a congenital or acquired hypofunction of the immune system had any detectable influence on the invariably high in vitro 3HdT-LI of TdT-positive bone marrow cells, a phenomenon possibly related to an autonomous and high turnover of this precursor cell compartment in the human bone marrow.
authors.affiliation: Institute for Clinical and Experimental Cancer Research, University of Berne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Hirt
authors.forename: A
authors.initials: A
authors.lastname: Morell
authors.forename: H
authors.initials: H
authors.lastname: Frei
authors.forename: P
authors.initials: P
authors.lastname: Imbach
authors.forename: H P
authors.initials: HP
authors.lastname: Wagner
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001402:B-Lymphocytes / Q000166:cytology; D001853:Bone Marrow / Q000473:pathology*; D002455:Cell Division; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000096:biosynthesis; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000473:pathology*; D007223:Infant; D007945:Leukemia, Lymphoid / Q000188:drug therapy / Q000473:pathology*; D008875:Middle Aged
chemical_list: D004247:DNA; D004254:DNA Nucleotidyltransferases; D004253:DNA Nucleotidylexotransferase