title: Thymic alterations in EphA4-deficient mice.
abstract: In the present work, we have demonstrated in vivo an altered maturation of the thymic epithelium that results in defective T cell development which increases with age, in the thymus of Eph A4-deficient mice. The deficient thymi are hypocellular and show decreased proportions of double-positive (CD4+CD8+) cells which reach minimal numbers in 4-wk-old thymi. The EphA4 (-/-) phenotype correlates with an early block of T cell precursor differentiation that results in accumulation of CD44-CD25+ triple-negative cells and, sometimes, of CD44+CD25- triple-negative thymocytes as well as with increased numbers of apoptotic cells and an important reduction in the numbers of cycling thymocytes. Various approaches support a key role of the thymic epithelial cells in the observed phenotype. Thymic cytoarchitecture undergoes profound changes earlier than those found in the thymocyte maturation. Thymic cortex is extremely reduced and consists of densely packed thymic epithelial cells. Presumably the lack of forward Eph A4 signaling in the Eph A4 -/- epithelial cells affects their development and finally results in altered T cell development.
authors.affiliation: Microscopy and Cytometry Center, Complutense University, 28040 Madrid, Spain.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Muñoz
authors.forename: David
authors.initials: D
authors.lastname: Alfaro
authors.forename: Javier
authors.initials: J
authors.lastname: García-Ceca
authors.forename: Luis M
authors.initials: LM
authors.lastname: Alonso-C
authors.forename: Eva
authors.initials: E
authors.lastname: Jiménez
authors.forename: Agustín
authors.initials: A
authors.lastname: Zapata
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008231:Lymphopenia / Q000235:genetics / Q000276:immunology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D018345:Mice, Knockout; D016513:Mice, SCID; D036122:Receptor, EphA4 / Q000172:deficiency* / Q000235:genetics*; D017154:Stromal Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D013950:Thymus Gland / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*
chemical_list: D036122:Receptor, EphA4