title: T cell specificity and cross reactivity towards enterobacteria, bacteroides, bifidobacterium, and antigens from resident intestinal flora in humans.
abstract: BACKGROUND
  T cell responses to normal intestinal bacteria or their products may be important in the immunopathogenesis of chronic enterocolitis.
  
  
  OBJECTIVE
  To investigate the T cell specificity and cross reactivity towards intestinal bacteria.
  
  
  METHODS
  T cell clones were isolated with phytohaemagglutinin from peripheral blood and biopsy specimens of inflamed and non-inflamed colon from five patients with inflammatory bowel disease (IBD) and two controls. T cell clones were restimulated with anaerobic Bacteroides and Bifidobacteria species, enterobacteria, and direct isolates of aerobic intestinal flora. T cell phenotype was analysed by single-cell immunocyte assay.
  
  
  RESULTS
  Analysis of 96 T cell clones isolated from peripheral blood and biopsy specimens from two patients with IBD showed that both Bifidobacterium and Bacteroides species specifically stimulate proliferation of CD4+TCRalphabeta+ T cell clones from both sites and that cross reactivity exists between these anaerobic bacteria and different enterobacteria. Analysis of 210 T cell clones isolated from three patients with IBD and two controls showed that indigenous aerobic flora specifically stimulate T cell clones from peripheral blood and biopsy specimens from a foreign subject. Some of these flora specific T cell clones were cross reactive with defined enterobacteria. In addition, T cell clones stimulated by their own indigenous aerobic flora were identified in patients with IBD.
  
  
  CONCLUSIONS
  Immune responses to antigens from the intestinal microflora involve a complex network of T cell specificities.
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology*; D001439:Bacteroides / Q000276:immunology*; D001644:Bifidobacterium / Q000276:immunology*; D002999:Clone Cells; D003093:Colitis, Ulcerative / Q000276:immunology; D003424:Crohn Disease / Q000276:immunology; D003429:Cross Reactions; D004755:Enterobacteriaceae / Q000276:immunology*; D005260:Female; D006801:Humans; D018928:Immunity, Mucosal; D015212:Inflammatory Bowel Diseases / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D013601:T-Lymphocytes / Q000276:immunology*