The effect of cyclosporin A on the endocrine pancreas of rats.

Treatment with the immunosuppressive agent Cyclosporin A frequently gives rise to alteration of function in the Langerhans islet which may result in diabetes. Light microscopy, immunocytochemical, and electron microscopic investigations demonstrate degranulation and vacuolization of B endocrine pancreatic cells in treated animals. Similar changes, but to a milder degree, are observed in the A-cells. The morphological alterations described are likely to result from an inhibition of the synthesis and secretion of B-cells.