title: Interleukin 16 expression and phenotype of interleukin 16 producing cells in Crohn's disease.
abstract: BACKGROUND
  The mechanisms involved in the initiation and maintenance of Crohn's disease are poorly understood. Previous studies have demonstrated an increased number of infiltrating CD4+ T cells within the inflammatory affected bowel wall in Crohn's disease. Novel therapy approaches using anti-CD4 antibodies are thought to be effective in Crohn's disease.
  
  
  OBJECTIVE
  Interleukin 16 (IL-16) has been characterised as a chemokine with selective chemoattraction for CD4+ inflammatory T cells. In this study, cellular expression of IL-16 in Crohn's disease and ulcerative colitis was investigated.
  
  
  METHODS
  Expression of IL-16 was analysed in tissue samples of Crohn's disease, ulcerative colitis, and normal controls by applying reverse transcription-polymerase chain reaction, non-radioactive in situ hybridisation, and immunohistochemistry. Double staining methods were used to characterise cells expressing IL-16. The amount of infiltrating CD4+ cells was determined by immunohistochemistry and correlated with the corresponding IL-16+ cell number by step sections.
  
  
  RESULTS
  An increased number of IL-16+ cells in Crohn's disease in comparison with ulcerative colitis and control probes was demonstrated. IL-16 was expressed by CD4 and CD8 positive T cells. In addition, in active Crohn's disease there was a substantial number of IL-16 positive mast cells. The increased number of CD4+ lymphocytes correlated positively with the increased number of IL-16 positive cells in Crohn's disease.
  
  
  CONCLUSIONS
  Our results demonstrate that increased expression of IL-16 in T cells and mast cells in active Crohn's disease is associated with increased numbers of CD4+ lymphocytes. Local expression of IL-16 seems to play a significant role in the initiation and persistence of the inflammatory process in Crohn's disease, presumably by IL-16 mediated recruitment of CD4+ cells, mostly lymphocytes, into the bowel wall.
authors.affiliation: Department of Pathology, Georg-August University of Göttingen, Germany. pmiddel@med.uni-goettingen.de
authors.forename: P
authors.initials: P
authors.lastname: Middel
authors.forename: K
authors.initials: K
authors.lastname: Reich
authors.forename: F
authors.initials: F
authors.lastname: Polzien
authors.forename: V
authors.initials: V
authors.lastname: Blaschke
authors.forename: B
authors.initials: B
authors.lastname: Hemmerlein
authors.forename: J
authors.initials: J
authors.lastname: Herms
authors.forename: M
authors.initials: M
authors.lastname: Korabiowska
authors.forename: H J
authors.initials: HJ
authors.lastname: Radzun
mesh_terms: D000293:Adolescent; D000328:Adult; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002634:Chemotaxis, Leukocyte; D003093:Colitis, Ulcerative / Q000276:immunology; D003106:Colon / Q000276:immunology; D003424:Crohn Disease / Q000276:immunology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D019410:Interleukin-16 / Q000032:analysis*; D008297:Male; D008407:Mast Cells / Q000276:immunology; D008875:Middle Aged; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D019410:Interleukin-16