Morphological effects of sodium fusidate (fusidin) on pancreatic islet cells: an electron microscopic study

Fusidic acid has been shown to prevent the lymphocyte co-stimulatory activities of cytokines and seems--in preliminary trials--clinically effective as an immunoregulatory drug e.g. in insulin-dependent diabetes mellitus. A toxic effect of fusidic acid may however be suspected since a previous study showed a significant dilatation of rough endoplasmic reticulum in cultured pancreatic islet cells from normal rats. In this study we examined the ultrastructural effects of the sodium salt of fusidic acid (fusidin) on cultured rat islet cells (treatment period 3-5 days), and of islet cells from rats receiving fusidin for 6 days. Electron microscopically, fusidin treatment in vitro (3 to 30 micrograms/ml) showed a significant dilatation of the rough endoplasmic reticulum of islet cells. No dose dependent changes were found. In the in vivo model no changes were demonstrated in concentrations of fusidin up to 9.64 micrograms/ml of homogenated pancreatic tissue. It is concluded that treatment with fusidin gives no detectable ultrastructural changes in vivo.