Immune-complex mediated colitis in rabbits. An experimental model.

An experimental colitis in rabbits is described, following the intravenous injection of preformed immune complexes of human serum albumin (HSA) and anti-HSA into non-sensitised rabbits. Tissue damage was localised to the colon by the Auer technique of inducing local non-specific inflammation, by the rectal instillation of dilute formalin. Formalin alone gave transient changes that reverted to normal within 24 hours. In rabbits given intravenous immune complexes formed in antigen-excess, a severe colitis was initiated, with histological features including mucosal ulceration, mixed inflammatory cell infiltration in the lamina propria, and crypt abscess formation. It is possible that immune-complex damage may be one of the pathogenic mechanisms involved in human ulcerative colitis.