title: Increased regulatory and decreased CD8+ cytotoxic T cells in the blood of patients with idiopathic pulmonary arterial hypertension.
abstract: BACKGROUND
  An association between pulmonary arterial hypertension (PAH) and various immune disorders is well established. Recently, the role of an intact immune system in protecting against pulmonary angioproliferation was shown in an animal model.
  
  
  OBJECTIVE
  To elucidate the role of T cells in human PAH, we comparatively studied T cell subclasses with emphasis on regulatory T cells (T(reg)) in the peripheral blood of patients with idiopathic pulmonary arterial hypertension (IPAH) and healthy controls.
  
  
  METHODS
  Isolated peripheral blood mononuclear cells from 36 patients diagnosed with IPAH and 33 healthy controls were stained with fluorescently labeled monoclonal antibodies against superficial T cell markers (CD3, CD4, CD8, CD25) and FoxP3, the intracellular marker of T(reg) cells. The relative cell distribution was analyzed by flow cytometry. The functionality of patient and control T(reg) cells was assessed by coculture of T(reg) with nonregulatory T cells from the same individual.
  
  
  RESULTS
  Significantly less CD8+ T cells (p = 0.02) and more CD25hi+ and FoxP3+CD4+ T cells were found in the peripheral blood of patients compared with controls (p = 0.009 and p < 0.001, respectively). The percentage of FoxP3+ cells within the CD25hi+CD4+ T(reg) cells was similar. T(reg) cell functionality was equal in patients and controls.
  
  
  CONCLUSIONS
  Our findings of decreased CD8+ T cells and increased T(reg) cells in the peripheral blood of patients with IPAH are novel and may have implications for directing future research in the field to elucidate the differential role of T cells and the immune system in IPAH.
authors.affiliation: University of Colorado Health Science Center, Denver, Colo., USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ulrich
authors.forename: Mark R
authors.initials: MR
authors.lastname: Nicolls
authors.forename: Laima
authors.initials: L
authors.lastname: Taraseviciene
authors.forename: Rudolf
authors.initials: R
authors.lastname: Speich
authors.forename: Norbert
authors.initials: N
authors.lastname: Voelkel
mesh_terms: D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood* / Q000503:physiopathology; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets; D011446:Prospective Studies; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000502:physiology*
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors