Enhanced CD3 monoclonal antibody induced proliferation of colonic mucosal T lymphocytes in Crohn's disease patients free of corticosteroid or immunosuppressor treatment.

Mucosal lymphocytes are increasingly activated in Crohn's disease. In order to investigate this phenomenon we tested the response of cultured colonic mucosal T lymphocytes to CD3 activation. These lymphocytes were obtained by biopsy from control subjects and Crohn's disease patients. T cells from mucosa involved in Crohn's disease showed a higher CD3-induced proliferative response compared to control T lymphocytes (P < 0.01). T cells from uninvolved areas showed a wide range of response, ranging from normal to very high proliferative indices. Our results suggest that the exaggerated response of mucosal T lymphocytes, due to the impairment of the downregulation of the CD3-dependent signaling process, may contribute to the pathogenesis of Crohn's disease.