Lysosomal storage in Swainsona spp. toxicosis: an induced mannosidosis

Ingestion of Swainsona spp. by grazing livestock results in a chronic disease characterized by neurological disturbances and intense vacuolation of cells in most organs. Experiments were carried out using Swainsona canescens and evidence is presented to show that tissues from affected animals contain high levels of mannose-rich oligosaccharides and that the plant contains an inhibitor of lysosomal alpha-mannosidase. It is concluded that ingestion of Swainsona induces a lysosomal storage disease, biochemically and morphologically similar to genetically determined mannosidosis. The role of this process in relation to Swainsona toxicosis is discussed.