Characterization of antigen-presenting dendritic cells in the peripheral blood and colonic mucosa of patients with ulcerative colitis

Objective Increased lymphocyte activation and production of inflammatory cy tokines are implicated in the pathogenesis of ulcerative colitis, Because a ntigen-presenting dendritic cells play a cardinal role in the activation an d survival of activated lymphocytes, the aim of the present study was to ch aracterize dendritic cells in ulcerative colitis. Design This study was designed to compare the phenotypes and functions of p eripheral blood dendritic cells among healthy normal volunteers and patient s with ulcerative colitis or Crohn's disease. Activated dendritic cells wer e also localized at the colonic mucosa, Methods Peripheral blood dendritic cells were generated from 15 patients wi th ulcerative colitis, 10 patients with Crohn's disease and 15 healthy cont rol volunteers. The stimulatory capacities of dendritic cells were analysed in an allogenic mixed lymphocyte reaction. Nitric oxide was detected by th e Griess method. Single- and dual-colour flow cytometry was employed to stu dy the levels of maturation of dendritic cells. Activated dendritic cells w ere localized immunohistochemically in the colonic mucosa, Results In comparison to normal controls, peripheral blood dendritic cells from patients with ulcerative colitis showed significantly increased stimul atory capacities (P <0.05) and produced significantly higher levels of nitr ic oxide (P <0.05). The numbers of activated dendritic cells were also sign ificantly higher in ulcerative colitis (P <0.05). Mature and activated dend ritic cells expressing the CD83 antigen were detected at the inflamed colon ic mucosa in patients with ulcerative colitis and Crohn's disease. Conclusions Activated and mature dendritic cells may have a role in the ind uction of an exacerbated immune response in ulcerative colitis, This study provides the scientific and logical basis for blocking the maturation and a ctivation of dendritic cells in ulcerative colitis as a new therapeutic int ervention. (C) 2001 Lippincott Williams & Wilkins.