Isolation and Characterization of Colonic Tissue-bound Antibodies from Patients with Idiopathic Ulcerative Colitis

To determine if specific anticolon antibodies bound to colonic mucosa occur in ulcerative colitis, we obtained surgical specimens of colon from five patients with ulcerative colitis, one patient with diverticulitis, and three control subjects with carcinoma. Two specimens of ileum and cecum were also obtained from patients with Crohn ileocolitis. Tissue was homogenized and washed and bound Ig was eluted by citrate buffer, pH 3.2. Concentrated eluates of all specimens from patients with ulcerative colitis reacted with antisera to kappa and gamma and not with antisera to alpha and mu chains. Corresponding eluates from all other specimens did not react with these antisera, but did react with antialbumin. The presence of IgG in ulcerative colitis eluates was also determined by immunoelectrophoresis, immunocoprecipitation, and affinity chromatography with antisera against human IgG. Indirect immunofluorescence and uptake of radiolabeled antibody demonstrated antigenic sites in diseased colonic epithelium of biopsy specimens obtained from six additional patients with ulcerative colitis and three patients with idiopathic proctitis, but not in patients with Crohn disease, nonspecific diarrhea, and bacillary dysentery and control subjects. Although the role of colitis colon-bound antibody in the pathogenesis of ulcerative colitis is unclear, local antibody-antigen complexes may initiate colonic epithelial cytolysis by various immunologically mediated mechanisms.