Immune status in Crohn's disease. 4. In vitro antibody dependent cell mediated cytotoxicity in peripheral blood

In Crohn's disease (CD) a potential etiopathogenetic role of the antibody dependent cell mediated cytotoxicity (ADCC) has been discussed. By means of a 51Cr release assay with an established human lymphoblastoid cell line as target, the in vitro ADCC activity was studied in the peripheral blood of 34 patients with CD. 11 patients with inflammatory bowel disease other than CD or ulcerative colitis (group D) and 45 sex and age matched healthy people served as controls. In unseparated mononuclear cell suspensions, we found a significantly lower ADCC activity in CD patients and in group D than in normals. Depletion of both phagocytic and plastic adherent cells, i.e. macrophages, resulted in complete normalisation of the ADCC activity in all patients of group D and also two-thirds of the CD patients. However, the remaining one third CD patients still exhibited ADCC activity below 1 standard deviation of normal. Most of these latter CD patients had highly active disease. Thus, this study showes that the general ADCC per se is normal in CD, except for a decrease in patients with high activity of disease. However, the normal general ADCC activity per se is significantly suppressed by phagocytic, plastic adherent cells. In this regard similar results were found in group D.