title: T cell development in mice expressing splice variants of the protein tyrosine phosphatase CD45.
abstract: The transmembrane protein tyrosine phosphatase CD45 is expressed in multiple isoforms as a result of alternative splicing of variable exons encoding the extracellular domain. CD45 expression is critical for T cell development, and thymocyte maturation is blocked at the immature CD4+ CD8+ double-positive stage in CD45 gene-deficient (CD45 -/-) mice. Moreover, splicing of variable CD45 exons changes during thymocyte selection. To test the role of CD45 extracellular splice variants in T cell selection and development, we introduced CD45RO (a low-m.w. splice variant lacking exons 4, 5, and 6) and CD45ABC (a high-m.w. isoform containing all exons) transgenes under the control of a thymocyte-specific promoter into a CD45 -/- background, generating CD45RO transgene-positive CD45 -/- (CD45RO) and CD45ABC transgene-positive CD45 -/- (CD45ABC) mice. We demonstrate that both CD45 splice isoforms can rescue development of CD4+ and CD8+ TCR-alphabeta+ thymocytes. Neither CD45 isoform rescued positive selection of H-Y TCR transgene thymocytes, and these cells were blocked at a HSA(high) CD69- CD5(low) stage of development. Peripheral T cells from CD45RO and CD45ABC mice proliferated in response to allogeneic stimulator cells and anti-CD3epsilon cross-linking. However, only CD45RO mice, not CD45ABC mice, generated cytotoxic T cell responses and neutralizing, Th cell-dependent IgG Abs after viral infections. In addition, we show that T cells from CD45RO and CD45ABC mice accumulate in lymph nodes but not in the spleen, liver, or skin, indicating that the CD45 phosphatase may control the homing behavior and trafficking of T cells.
authors.affiliation: Department of Medical Biophysics, University of Toronto, Ontario, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Kozieradzki
authors.forename: T
authors.initials: T
authors.lastname: Kündig
authors.forename: K
authors.initials: K
authors.lastname: Kishihara
authors.forename: C J
authors.initials: CJ
authors.lastname: Ong
authors.forename: D
authors.initials: D
authors.lastname: Chiu
authors.forename: V A
authors.initials: VA
authors.lastname: Wallace
authors.forename: K
authors.initials: K
authors.lastname: Kawai
authors.forename: E
authors.initials: E
authors.lastname: Timms
authors.forename: J
authors.initials: J
authors.lastname: Ionescu
authors.forename: P
authors.initials: P
authors.lastname: Ohashi
authors.forename: J D
authors.initials: JD
authors.lastname: Marth
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
authors.forename: J M
authors.initials: JM
authors.lastname: Penninger
mesh_terms: D017398:Alternative Splicing / Q000276:immunology*; D000818:Animals; D015704:CD4 Antigens; D016827:CD8 Antigens; D002454:Cell Differentiation / Q000276:immunology; D002465:Cell Movement / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D005260:Female; D006182:H-Y Antigen / Q000235:genetics; D017578:Immunoglobulin Class Switching; D007536:Isomerism; D017493:Leukocyte Common Antigens / Q000235:genetics*; D008198:Lymph Nodes / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008822:Mice, Transgenic; D017027:Protein Tyrosine Phosphatases / Q000235:genetics*; D016693:Receptors, Antigen, T-Cell, alpha-beta; D013601:T-Lymphocytes / Q000166:cytology* / Q000201:enzymology*; D006377:T-Lymphocytes, Helper-Inducer / Q000821:virology; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology; D014721:Vesicular stomatitis Indiana virus / Q000276:immunology
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D006182:H-Y Antigen; D016693:Receptors, Antigen, T-Cell, alpha-beta; D017493:Leukocyte Common Antigens; D017027:Protein Tyrosine Phosphatases