title: Peripheral monocyte and naive T-cell recruitment and activation in Crohn's disease.
abstract: OBJECTIVE
  Transmural perivascular mononuclear cell infiltrates are a feature of Crohn's disease. The aim of this study was a molecular characterization of the mechanisms leading to the formation of these infiltrates.
  
  
  METHODS
  Endothelial cell and leukocyte expression of the adhesion molecules directing leukocyte transendothelial migration were studied in situ by immunohistochemical analysis of 10 samples from patients with Crohn's disease and 10 samples from normal controls. Double-staining methods were used to characterize the cells forming the infiltrates.
  
  
  RESULTS
  CD11a+ and L-selectin-positive mononuclear cells seemed to be the major component of perivascular infiltrates. The vast majority of these cells were CD68+, CD31+ monocytes/macrophages surrounded by CD3+, L-selectin-positive, CD31+, CD45RA+, and/or CD45RO+ T lymphocytes. T lymphocytes within the vessels expressed both CD45RA and CD45RO markers. Endothelial cells were intercellular adhesion molecule 1 positive and mostly CD34+. Strong adhesion between L-selectin-positive and CD11a+ intravascular mononuclear cells and CD34+ and intercellular adhesion molecule 1-positive endothelial cells were observed.
  
  
  CONCLUSIONS
  Data indicate that peripheral mononuclear cells are actively recruited in the submucosa of Crohn's disease tissue; endothelial cells express adhesion molecules highly permissive for transendothelial migration of monocytes and both naive and memory T cells contributing to infiltrates generation; and close membrane contact between migrated macrophages and naive T cells leads to the T-cell transition from naive to memory phenotype within Crohn's disease.
authors.affiliation: Istituti di Clinica Medica 1, Università La Sapienza, Rome, Italy.
authors.forename: V L
authors.initials: VL
authors.lastname: Burgio
authors.forename: S
authors.initials: S
authors.lastname: Fais
authors.forename: M
authors.initials: M
authors.lastname: Boirivant
authors.forename: A
authors.initials: A
authors.lastname: Perrone
authors.forename: F
authors.initials: F
authors.lastname: Pallone
mesh_terms: D017252:CD3 Complex / Q000032:analysis; D002465:Cell Movement; D003424:Crohn Disease / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D007413:Intestinal Mucosa / Q000473:pathology; D019041:L-Selectin / Q000032:analysis; D008213:Lymphocyte Activation; D016169:Lymphocyte Function-Associated Antigen-1 / Q000032:analysis; D009000:Monocytes / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D017252:CD3 Complex; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1; D019041:L-Selectin