title: Impaired expansion of mouse B cell progenitors lacking Btk.
abstract: Mutations in the gene encoding the protein tyrosine kinase Btk are associated with the human B cell immunodeficiency X-linked agammaglobulinemia (XLA). In the mouse, a point mutation in the Btk pleckstrin homology domain segregates with a milder X-linked immunodeficiency (xid). To assess the importance of Btk function in murine lymphopoiesis, we generated multiple embryonic stem cell clones bearing a targeted disruption of the btk gene and examined their potential to produce lymphocytes in both C57BL/6 and RAG2-/- host chimeric animals. These mice provide a complementary set of in vivo competition assays that formally establish the genetic basis for the xid phenotype. Although the null mutation yields a phenotype quite similar to that of xid, it also compromises expansion of B cell precursors. Our results suggest that the murine and human consequences of Btk deficiency differ only quantitatively, and represent the same disease process.
authors.affiliation: Department of Immunology, University of Washington, Seattle 98195, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Kerner
authors.forename: M W
authors.initials: MW
authors.lastname: Appleby
authors.forename: R N
authors.initials: RN
authors.lastname: Mohr
authors.forename: S
authors.initials: S
authors.lastname: Chien
authors.forename: D J
authors.initials: DJ
authors.lastname: Rawlings
authors.forename: C R
authors.initials: CR
authors.lastname: Maliszewski
authors.forename: O N
authors.initials: ON
authors.lastname: Witte
authors.forename: R M
authors.initials: RM
authors.lastname: Perlmutter
mesh_terms: D000077329:Agammaglobulinaemia Tyrosine Kinase; D000361:Agammaglobulinemia / Q000235:genetics; D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D001483:Base Sequence; D002678:Chimera; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D006801:Humans; D018655:Lymphocyte Count; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D011505:Protein-Tyrosine Kinases / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology; D014960:X Chromosome
chemical_list: D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human; C000625951:Btk protein, mouse