Experimental hypersensitivity reactions in the colon and the problem of ulcerative colitis

Summary and conclusions

1. The gastrointestinal tract, anatomically, biologically, and physiologically, seems capable of participating in or generating immunologic reactions.

2. Hypersensitivity phenomena such as the Arthus and Auer reactions and the immunologically nonspecific Shwartzman response can be produced in the rabbit colon.

3. The principal features of the Shwartzman reaction in the rabbit colon are edema, severe hemorrhage, vascular thromboses, intense leukocytic infiltration, and subsequent granuloma formation.

4. The main features of the Arthus reaction in the rabbit colon are edema, cellular infiltration with lymphocytes, plasma cells, and eosinophils, hemorrhage, and later formation of granulomas.

5. An “Auer colitis” can be induced in sensitized rabbits under conditions presumably facilitating antigen-antibody interaction in the colon.

6. The “Auer colitis” is characterized grossly by inflammation, hemorrhage and ulceration; and histologically by pronounced cellular infiltration, ulceration, and occasional perivascular infiltration. Repeated Auer responses result in chronic inflammation, distortion of the glandular pattern, fibrosis of the lamina propria and submucosa, accumulation of lymphocytes, and occasional atrophy of the colonic mucosa.

7. While some clinical, laboratory, and anatomic features of ulcerative colitis appear in accord with the possibility of an immunologic component, conclusive evidence for an immunologic or an autoimmune reaction in ulcerative colitis is yet to be obtained.