Reduced CD1d expression in colonic epithelium in microscopic colitis.

Abstract: CD1d is a member of a major histocompatibilitycomplex class I-like molecule family. Its function may involvepresenting microbial nonpeptide or lipidic antigens to Tlymphocytes, therefore to serve as an important factor innormal mucosal immunity of the gastrointestinal tract. In thisstudy, the expression level of CD1d in microscopic colitis (ie,collagenous and lymphocytic colitis) was examined, andcompared with that in normal colonic mucosa. Formalin-fixed,paraffin-embedded colon biopsies with diagnosis of lymphocyticcolitis (19 cases), collagenous colitis (6 cases), and no pathologicchange (20 cases) were studied immunohistochemically usingmonoclonal antibodies against human CD1d, CD3, CD4, andCD8. CD1d staining in the epithelium and lamina propria wasgraded along a scale of 0 to 4. Intraepithelial CD3-positivelymphocytes were counted in an area of 300 epithelial cells foreach specimen. The results show that CD1d was expressed innormal colonic epithelial cells, primarily on the basolateralmembranes with a concentrated intracellular pool in thesubnuclear region. The expression level was markedly reducedin both lymphocytic colitis (P<0.001) and collagenous colitis(P<0.001), along with a significant increase in the number ofintraepithelial CD3/CD8 lymphocytes (P<0.001). These find-ings suggest that microscopic colitis is associated with decreasedepithelial expression of CD1d, an important immunoregulatorymolecule in the gastrointestinal tract.Key Words: CD1d, microscopic colitis, chronic colitis, collage-nous colitis, lymphocytic colitis, mucosal immunity, inflamma-tory bowel disease(Appl Immunohistochem Mol Morphol 2006;14:309–313)