title: Increased frequency of intestinal CD4+ T cells reactive with mycobacteria in patients with Crohn's disease.
abstract: OBJECTIVE
  The aim of this study was to assess the frequency of mycobacteria and Escherichia coli reactive T cells in intestinal biopsies from patients with Crohn's disease (CD) and ulcerative colitis (UC).
  
  
  METHODS
  The biopsies were obtained by colonoscopy from adult patients with active CD (n = 5) and active UC (n = 4). The number of CD4+ T cell clones expanded and screened from each patient varied from 383 to 3972 giving a total of 16639 individual clones. The T cell clones were tested for responses to Mycobacterium avium subspecies paratuberculosis (MAP) and E. coli. The cytokine profile of 42 individual T cell clones from four CD patients was assessed.
  
  
  RESULTS
  The frequency of mycobacteria reactive T cell clones in CD patients ranged from 0.17 to 1.63% and was higher (p = 0.038) than the frequency of E. coli reactive T cells ranging from 0 to 0.18%. No or very low numbers of mycobacteria reactive clones were detected in three UC patients while the fourth UC patient had a frequency similar to what was observed in CD patients. The frequencies of E. coli reactive T cell clones in UC patients ranged from 0 to 0.52%. T cell clones (n = 42) from CD patients all produced IL-17 and/or IFN-γ. Several clones were also able to produce IL-10.
  
  
  CONCLUSIONS
  The high frequency of intestinal tissue resident T cells reactive to mycobacteria suggests that an adaptive immune response have taken place and argues that these bacteria may contribute to the chronic inflammation in CD.
authors.affiliation: Centre for Immune Regulation and Department of Immunology, Oslo University Hospital-Rikshospitalet , Oslo , Norway.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Olsen
authors.forename: Knut E
authors.initials: KE
authors.lastname: Lundin
authors.forename: Ludvig M
authors.initials: LM
authors.lastname: Sollid
mesh_terms: D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D002999:Clone Cells; D003093:Colitis, Ulcerative / Q000276:immunology / Q000473:pathology*; D003113:Colonoscopy; D003424:Crohn Disease / Q000276:immunology / Q000382:microbiology / Q000473:pathology*; D004926:Escherichia coli / Q000502:physiology*; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism; D020381:Interleukin-17 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D016927:Mycobacterium avium subsp. paratuberculosis / Q000502:physiology*
chemical_list: D020381:Interleukin-17; D016753:Interleukin-10; D007371:Interferon-gamma