HETEROGENEOUS EXPRESSION OF CARCINOEMBRYONIC ANTIGEN IN THE NORMAL COLON AND UP-REGULATION IN ACTIVE ULCERATIVE-COLITIS

Using a technique of tolerization, a murine monoclonal antibody (MAb 2 E8) has been raised,which displays regional differences in reactivity in the epithelium of the normal human colon and increased reactivity i n active ulcerative colitis, MAb 2E8 (IgG(1)) was highly colon-specifi c and gave higher immunoperoxidase staining scores in the proximal col onic mucosa compared with paired rectal sections (P<0.02). Expression of the antigen reactive with MAb 2E8 was enhanced in active ulcerative colitis compared with quiescent ulcerative colitis (P<0.05) and norma l controls (P<0.001). Western blotting and indirect immunofluorescent screening on transfected cell lines established that MAb 2E8 was react ive with carcinoembryonic antigen (CEA), This is the first demonstrati on of regional differences in the expression of CEA in the normal colo n and indicates upregulation of this molecule in active ulcerative col itis.