Autoantibody production in rabbits. VII. Autoantibodies to gut produced by the injection of bacteria.

Rabbits received two injections of dead bacteria in Freund's complete adjuvant. One month later the sera of the rabbits were examined for autoantibodies against gut by indirect immunofluorescence using the rabbit's own stomach, ileum and colon taken at post mortem. Autoantibodies against colon were found in three out of seven rabbits injected with one particular strain of O64 and in a few animals injected with other and . The antigen, with which the autoantibodies reacted, behaved like mucus and was detected in the colon and sometimes in the ileum and the stomach. Three patterns of staining were observed: (a) staining of the superficial mucosa of the colon with sparing of the deep glands; (b) staining of scattered groups of glands in the deepest part of the colon with sparing of the superficial glands (this pattern of staining was associated with staining of the superficial mucosa of the body of the stomach); and (c) staining of both the superficial and deep glands of the colon. None of the sera tested reacted with the bronchial or salivary glands. Polysaccharide preparations of the colon, but not the stomach, inhibited the reaction of the autoantibodies with colon in the sera tested. The amount of antigen needed to inhibit the basal staining was much greater than that needed to inhibit the superficial staining. It was concluded that rabbits may produce autoantibodies to colon and in some cases to ileum and stomach following the injection of certain dead bacteria in Freund's complete adjuvant.