Anti-CD4 Therapy Decreases Epithelial Expression of HLA-DR Molecules in Patients with Crohn’s Disease

Mucosal cells from patients with Crohn’s disease regularly express HLA-class II antigens, which are thought to be induced by cytokines, in particular interferon gamma, that are secreted by activated T-cells. Abberant MHC-class II expression by epithelial cells may play a role in diseases characterized by T-cell activation. Activated CD4-positive T-cells are present in the lamina propria of patients with Crohn’s disease. In this study we report the results of an open label, single center anti-CD4 ˜ trial in patients with steroid refractory Crohn’s disease. A rapid and near complete loss of HLA-DR expression by mucosal cells was observed in 10 out of 12 patients, following infusion of the chimeric anti-CD4 antibody M-T412. These results suggest that CD4-positive T-cells are necessary for epithelial class II expression in patients with Crohn’s disease.