Interleukin 16 expression and phenotype of interleukin 16 producing cells in Crohn's disease.
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.
Middel
P
P
Department of Pathology, Georg-August University of Göttingen, Germany. pmiddel@med.uni-goettingen.de
Reich
K
K
Polzien
F
F
Blaschke
V
V
Hemmerlein
B
B
Herms
J
J
Korabiowska
M
M
Radzun
H J
HJ
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*
D019410:Interleukin-16