title: Reduced neointima formation after arterial injury in CD4-/- mice is mediated by CD8+CD28hi T cells.
abstract: BACKGROUND
  CD8(+) T-cell activation, characterized by increased CD28 expression, reduces neointima formation after arterial injury in mice. The CD8(+)CD28(hi) phenotype is associated with increased effector function. In this study, we used a mouse model that has CD8(+) but no CD4(+) T cells (CD4-/-) to assess the role of CD8(+) T cells and test the function of CD8(+)CD28(hi) T cells in modulating neointima formation after arterial injury.
  
  
  RESULTS
  Neointima formation after pericarotid arterial cuff injury was significantly less in CD4-/- mice compared with wild-type (WT) mice. Negligible baseline lytic activity by splenic CD8(+) T cells from uninjured WT mice against target syngeneic smooth muscle cells was significantly increased 7 days after injury. Interestingly, CD8(+) T cells from uninjured CD4-/- mice had significant lytic activity at baseline that remained elevated 7 days after injury. CD8(+) T-cell lytic activity was significantly reduced by depletion of CD28(hi) cells. CD8(+)CD28(hi) T cells adoptively transferred into recipient Rag-1-/- mice significantly reduced neointima formation compared with CD8(+)CD28(+) T-cell recipient mice.
  
  
  CONCLUSIONS
  CD8(+) T cells reduced neointima formation after arterial injury, attributed in part to increased function of the CD8(+)CD28(hi) phenotype.
authors.affiliation: Oppenheimer Atherosclerosis Research Center, Division of Cardiology, Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA. dimayugap@cshs.org
authors.forename: Paul C
authors.initials: PC
authors.lastname: Dimayuga
authors.forename: Kuang-Yuh
authors.initials: KY
authors.lastname: Chyu
authors.forename: Wai Man
authors.initials: WM
authors.lastname: Lio
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Zhao
authors.forename: Juliana
authors.initials: J
authors.lastname: Yano
authors.forename: Jianchang
authors.initials: J
authors.lastname: Zhou
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Honjo
authors.forename: Prediman K
authors.initials: PK
authors.lastname: Shah
authors.forename: Bojan
authors.initials: B
authors.lastname: Cercek
mesh_terms: D000818:Animals; D001158:Arteries / Q000293:injuries*; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology*; D008297:Male; D051379:Mice; D058426:Neointima / Q000276:immunology*; D057772:Vascular System Injuries / Q000150:complications*
keywords: CD8+ T cells; cytolytic activity; neointima; vascular smooth muscle cells