PT - JOURNAL ARTICLE AU - P Middel AU - K Reich AU - F Polzien AU - V Blaschke AU - B Hemmerlein AU - J Herms AU - M Korabiowska AU - H-J Radzun TI - Interleukin 16 expression and phenotype of interleukin 16 producing cells in Crohn's disease AID - 10.1136/gut.49.6.795 DP - 2001 Dec 01 TA - Gut PG - 795--803 VI - 49 IP - 6 4099 - http://gut.bmj.com/content/49/6/795.short 4100 - http://gut.bmj.com/content/49/6/795.full SO - Gut2001 Dec 01; 49 AB - 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.AIMS 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.CONCLUSION 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.ILinterleukinCDCrohn's diseaseUCulcerative colitisNIGDnon-inflammatory gut disorderRT-PCRreverse transcription-polymerase chain reactionmAbmonoclonal antibodyFITCfluorescein isothiocyanate