This study looked at the intestinal permeability and the immune response to enteric
bacterial antigens in patients with
inflammatory bowel disease (IBD). They were evaluated by using a
lactulose tolerance test and measuring blood anti-
lipid A antibody concentrations, respectively. The
lactulose tolerance tests were performed 22 times in 14 patients with
Crohn's disease (CD), 19 times in 12 patients with
ulcerative colitis (UC), and 12 times in 12 healthy controls. Blood
lactulose concentrations were measured after
oral administration every two hours for eight hours, also blood
C reactive protein concentrations and anti-
lipid A antibody concentrations were measured just before
lactulose administration. Blood
lactulose concentrations were significantly higher in patients with CD than in the controls from two to eight hours after administration, while in UC they were significantly higher than in the controls from six to eight hours. Maximum blood
lactulose concentrations in each tolerance test in patients with the active phase significantly exceeded those in the inactive phase of either CD or UC. A significant correlation was also seen between the maximum blood
lactulose concentrations and the
C reactive protein concentrations. Blood anti-
lipid A antibody concentrations in patients with CD were significantly higher than in the controls as well as in patients with UC in
immunoglobulin (Ig) A class and
IgG class. In UC they were significantly higher than in the controls in
IgA class. But, they were not related to the severity of the disease of either CD or UC, and not correlated significantly with the maximum blood
lactulose concentrations in either CD or UC. The intestinal permeability and the immune response to enteric
bacterial antigens in patients with inactive CD were significantly increased over those in the controls as well as in patients with inactive UC. These findings suggest that an increase of the intestinal permeability and that of producing
antibodies to enteric
bacterial antigens are both important for the pathogenesis of IBD, and that the characteristics of CD and UC differ.