title: Exacerbated colitis associated with elevated levels of activated CD4+ T cells in TCRalpha chain transgenic mice.
abstract: OBJECTIVE
  An unconventional CD4+ TCRalpha(-)beta(+) cell population mediates the development of colitis resembling ulcerative colitis in T-cell receptor alpha mutant (TCRalpha(-/-)) mice. However, the significance of such T cells in individuals with an intact TCRalpha locus remains unclear. Because a substantial proportion of naturally rearranged TCRalpha chains fails to pair with TCRbeta chains, the aim of this study was to analyze the development of CD4+ TCRalpha(-)beta(+) cells and the course of colitis in the presence of such a TCRalpha chain.
  
  
  METHODS
  TCR chain transgenic TCRalpha(-/-) mice were generated and compared with wild-type and TCRalpha(-/-) mice by flow cytometric analysis of T lymphocytes with respect to their TCR expression and activation status and by histological analysis of colon tissue. The colitogenic potential of the unconventional CD4+ TCRalpha(-)beta(+) cells was assessed by adoptive transfer experiments. Furthermore, the half-life of TCRbeta chains was determined by pulse-chase labeling and immunoprecipitation.
  
  
  RESULTS
  Transgenic expression of a TCR Valpha7.2 chain led to increased frequencies of CD4+ TCRalpha(-)beta(+) cells that caused rapid onset of colitis, reminiscent of, but even more severe than, that in TCRalpha(-/-) mice. This unconventional T-cell population displayed a constitutively activated phenotype in normal and transgenic TCRalpha(-/-) mice. An extended half-life of newly synthesized TCRbeta chains suggests a chaperone function of the TCR Valpha7.2 chain in TCRalpha(-/-) mice.
  
  
  CONCLUSIONS
  Physiological TCRalpha rearrangement can promote the formation of chronically activated CD4+ TCRalpha(-)beta(+) T cells and may play a role in the etiology of UC.
authors.affiliation: Department of Immunology, Max Planck Institute for Infection Biology, Berlin, Germany.
authors.forename: Immo
authors.initials: I
authors.lastname: Prinz
authors.forename: Uwe
authors.initials: U
authors.lastname: Klemm
authors.forename: Stefan H E
authors.initials: SH
authors.lastname: Kaufmann
authors.forename: Ulrich
authors.initials: U
authors.lastname: Steinhoff
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002470:Cell Survival; D003092:Colitis / Q000473:pathology / Q000503:physiopathology*; D003106:Colon / Q000473:pathology / Q000503:physiopathology; D015321:Gene Rearrangement; D006207:Half-Life; D008214:Lymphocytes; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012720:Severity of Illness Index; D013950:Thymus Gland / Q000473:pathology / Q000503:physiopathology
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta