Development of ulcerative colitis-associated anti-idiotype antibody using a novel monoclonal antibody against a colonic autoantigen.

Earlier studies have established reactivity of ulcerative colitis colon-bound IgG antibody with an autoantigen recognized by a novel monoclonal antibody, 7E12H12 (IgM isotype). Purified 7E12H12-IgM was used to raise anti-idiotype antibody in the rabbit, and the presence of disease-specific idiotype(s) was evaluated in patients with ulcerative colitis. F(ab')2 fragments were prepared from serum-IgG of the rabbit immunized with 7E12H12-IgM and extensively absorbed against unrelated mouse IgM and purified serum IgG from 4 normal subjects. The reactivity of the absorbed F(ab')2 fragment was tested in an ELISA against the serum from 19 patients with ulcerative colitis, 15 patients with Crohn's disease, and 10 normal subjects. The OD values with ulcerative colitis sera were significantly (P < 0.0005) higher than those with Crohn's disease and normal sera. Blood serum from 84% of patients with ulcerative colitis contains antibodies that are reactive to the F(ab')2 fragments of the immune rabbit serum-IgG. Further studies of the anti-idiotype antibodies may elucidate autoimmune processes in ulcerative colitis and may have diagnostic and therapeutic values.