The dynamics of inflammation of the anterior eye in a novel experimental model for hypersensitivity

A novel immunologically provoked inflammatory process was studied in guinea pigs. The animals were immunized by i.p. injections of ovalbumin (OA) suspended in Freund's complete adjuvant and challenged by the application of OA into the conjunctival sac of one eye. An inflammatory reaction was seen a few minutes after provocation and lasted normally for 4-7 days. The process was characterized by early damage to the epithelial layer which was partly detached in small flakes; an intense tearing with the tear fluid soon turning mucous and then purulent; vasodilation in the bulbar conjunctiva, in particular towards the limbal region; margination and emigration of polymorphonuclear, and to a lesser extent, eosinophil, leucocytes which migrated towards and infiltrated the surface epithelial layer. Subsequently, the dominant cell type infiltrating the submucosa was lymphocytes. Later, opacity of the cornea occurred, probably due to oedema and neovascularization of the stroma progressing centrally from the periphery. When the antigenic challenge was repeated, thickening of the conjunctival mucosa, and neoformation of collagen bundles in the submucosa led to the swelling of the upper lids. The facets of this inflammatory trauma may not fit easily into any of the classical types of hypersensitivity. Rather, it may combine features of several of them, at least type 1 and type 4. This syndrome shows several features similar to those of human vernal keratoconjunctivitis.