Electron microscopy of nephropathia epidemica cell nuclei in kidney biopsies

Ultrastructural changes in cell nuclei were studied in kidney biopsies from 18 patients suffering from Nephropathia epidemica. Three patients showed small nuclear particles in a large aggregate in a few cells of the distal tubule. The particles had a diameter of about 30 nm and their occurrence was not associated with intravenous glucose infusions. Large light nuclear bodies were numerous in the nuclei of both interstitial and tubular cells. Many showed strands of darker material about 35 nm in diameter at their center. Nuclear vesicles with varying amounts of membrane debris were seen in both tubular and interstitial cells. Occasional interstitial lymphocytes showed abnormal margination of chromatin. Of the changes observed the small nuclear particles are not found in kidney biopsies in other conditions and it is possible that they are aggregates of viral protein.