EXPRESSION OF ADHESION MOLECULES AND HLA-DR BY MACROPHAGES AND DENDRITIC CELLS IN APHTHOID LESIONS OF CROHNS-DISEASE - AN IMMUNOCYTOCHEMICAL STUDY

The phenotypes and ultrastructure of macrophages and dendritic cells i n aphthoid lesions of the colon were immunocytochemically observed in patients with Crohn's disease. Biopsy specimens were endoscopically ob tained from both aphthoid and advanced lesions in Crohn's disease pati ents. Biopsy specimens obtained from patients with infectious colitis and from normal individuals served as controls. Aphthoid lesions conta ined densely aggregated CD68+ macrophages, which were surrounded by nu merous ID-1+ dendritic cells. In the normal controls and infectious co litis patients, however, a few scattered CD68+ macrophages and ID-1+ d endritic cells were noted beneath the surface epithelium. CD3+ lymphoc ytes were significantly increased in both aphthoid and advanced lesion s of Crohn's disease, but the CD4/CD8 ratio was similar in all groups studied. The double immunoperoxidase staining method revealed that bot h CD68+ macrophages and ID-1+ dendritic cells in the aphthoid lesions simultaneously expressed ICAM-1 and HLA-DR antigens. Electronmicroscop ic observation revealed that CD68+ macrophages had numerous vesicles a nd lysosomal granules and few projections, and that ID-1+ dendritic ce lls had appreciable cytoplasmic protrusions with a few vacuoles. These findings suggested that the colonic mucosa in Crohn's disease contain ed two types of macrophage/dendritic cells in the same lineage that ex pressed intercellular adhesion molecules and class-II MHC antigens. It also appeared that the aphthoid lesions of Crohn's disease featured a n increase in macrophages and dendritic cells consistent with immunolo gical activation.