ACTIVATION OF EOSINOPHILS IN THE PATHOPHYSIOLOGY OF ULCERATIVE-COLITIS

We studied the role of eosinophils as effector cells in the pathophysi ology of ulcerative colitis. In the active stage of this disease, the colonic mucosa exhibited infiltration of numerous eosinophils positive to the EG(2) antibody, which reacts specifically with the secretory f orm of eosinophil cationic protein. Electron microscopic studies demon strated that the eosinophils had specific granules in various stages o f degranulation. Hence, it is strongly suggested that the eosinophils infiltrating the inflamed mucosa are activated and may induce tissue d amage during the degranulation and release of this cationic protein. C hanges in the levels of serum eosinophil cationic protein in 14 patien ts who remained in long-term remission were studied. Four of these pat ients showed persistently high concentrations of eosinophil cationic p rotein (equal to or greater than 30 mu-g/l) and persistently high perc entage (mean, 30.2%) of hypodense eosinophils (specific gravity less t han 1.082) in peripheral blood. Such findings were associated with mil d active disease at colonoscopy. These features suggest that the activ ation of eosinophils is one of the factors that contribute to the chro nic inflammation in ulcerative colitis.