Human colonic intraepithelial lymphocytes from patients with inflammatory bowel disease fail to down-regulate proliferative responses of primed allogeneic peripheral blood mononuclear cells after rechallenge with antigens.

Human colonic intraepithelial lymphocytes from control subjects down-regulate the proliferative responses of primed allogeneic peripheral blood mononuclear cells on rechallenge with antigens or phytohaemagglutinin (PHA). In contrast, human colonic intraepithelial lymphocytes from patients with inflammatory bowel disease fail to down-regulate the proliferative responses of primed allogeneic peripheral blood mononuclear cells on rechallenge with antigens. These findings may be important in the development and maintenance of the mucosal immunological activation of inflammatory bowel disease.