Experimental brucei trypanosomiasis: Immunosuppression of the blood-aqueous barrier

Abstract

Experimental Trypanosoma brucei infection induces intense protein leakage into the anterior chamber of cats' and dogs' eyes, with a cyclitis-like symptomatology, preceded by hypersensitivity of conjunctiva and respiratory mucosae, together with lacrimation, and facial oedema. The pherogram of the aqueous humor is the replica of the serum pherogram at the end-stage of the disease, and is identical to that of secondary aqueous. Absence of any significant changes in serum proteins and immunoglobulins, and the poor cellular reaction at tissue level point towards immune unresponsiveness subsequent to experimental protozoal infection. Light microscopy reveals, at the level of the ciliary processes two kinds of cystic formation, the walls of which are formed by ciliary epithelium. One type contains amorphous material next to trypanosomes, macrophages and plasmocyte-like cells; the second type contains also fibrillar structures possibly collagen. Ultramicroscopy suggests these cystic formations to be enlarged ciliary channels. The fenestrated capillary wall showed no changes, either after withdrawal of aqueous, or after toxic parasite-action; the presence of large protein molecules and trypanosomes in the anterior chamber is due to damage to the ciliary epithelium.