title: Adenosine deaminase and thymocyte maturation.
abstract: The congenital absence of adenosine deaminase in humans results in severe combined immunodeficiency. To clarify the process whereby thymocytes are destroyed in the absence of adenosine deaminase activity, we induced a parallel condition in mice through the injection of an inhibitor of adenosine deaminase, deoxycoformycin. We have observed that deoxycoformycin, in addition to maintaining high levels of dATP in thymocytes, blocks the progression of thymocyte differentiation at two points. As a result of the first block, the cortex is depleted of immature cortical thymocytes while CD4+CD8+ thymocytes with functionally rearranged T-cell receptors survive. As a result of the second block, the CD4+CD8+ thymocytes are prevented from further differentiation to mature CD4+CD8- or CD4-CD8+ T lymphocytes and accumulate at the corticomedullar junction and in the medulla. These observations suggest that the maintenance of dNTP pools by adenosine deaminase is critical to at least two stages of thymocyte differentiation.
authors.affiliation: Division of Immunology/Rheumatology, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Doherty
authors.forename: S
authors.initials: S
authors.lastname: Pan
authors.forename: J C
authors.initials: JC
authors.lastname: Mulloy
authors.forename: E
authors.initials: E
authors.lastname: Thompson
authors.forename: P
authors.initials: P
authors.lastname: Thorner
authors.forename: J
authors.initials: J
authors.lastname: Barankiewiecz
authors.forename: C M
authors.initials: CM
authors.lastname: Roifman
authors.forename: A
authors.initials: A
authors.lastname: Cohen
mesh_terms: D000243:Adenosine Deaminase / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D000831:Animals, Newborn; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D001483:Base Sequence; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens; D002454:Cell Differentiation / Q000187:drug effects; D005434:Flow Cytometry; D016130:Immunophenotyping; D051379:Mice; D008969:Molecular Sequence Data; D015649:Pentostatin / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology / Q000201:enzymology / Q000254:growth & development*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D015704:CD4 Antigens; D016827:CD8 Antigens; D011948:Receptors, Antigen, T-Cell; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015649:Pentostatin; D000255:Adenosine Triphosphate; D000243:Adenosine Deaminase