Mucosal cell-mediated immunity to mycobacterial, enterobacterial and other microbial antigens in inflammatory bowel disease

SUMMARY Culture studies have suggested that Mycobacterium paratuherculosis may play a role in the aetiology of Crohn's disease. However, evidence of sensilizalion to mycobactcrial antigens amongst patients with Crohn's disease has not yet been adequately demonstrated. Previous studies of cell-mediated immunity (CMI) in Crohn's disease were restricted to responses of peripheral blood mononuclcar cells (PBMC) to mycobacterial antigens. In this study we have investigated the proliferativc responses of both PBMC and mesenteric lymph node mononuclcar cells (MLNMC) to a range of mycobacterial and non-mycobactcrial antigens. There was no evidence of specific sensitization in the responses of MLNMC and PBMC from patients with inflammatory bowel disease (IBD) to the mycobacterial antigens. However, anergy to M. paratuherculosis could not be excluded. IBD MLNMC responses to most antigens were generally greater than those of PBMC. which were often undetectable. When compared with controls, there was evidence of increased CM 1 to a range of non-mycobactcrial antigens, especially Yersinia enterocolitica. amongst both MLNMC and PBMC from patients with Crohn's disease and ulcerative colitis (UC). These results do not provide support to the proposed role of mycobacteria in the pathogcnesis of Crohn's disease, but indicate that further investigation may determine a role for bacterial-specific T cell-mediated responses in the palhogcncsis of IBD.