Cytokines, adhesion molecules, and cellular infiltration in nephropathia epidemica kidneys: an immunohistochemical study.

Puumala hantavirus-induced nephropathia epidemica (NE) is an important cause for an acute reversible renal failure in Scandinavia, European Russia, and the Balkans. The characteristic histopathological renal finding is an acute tubulointerstitial nephritis. Mild to massive proteinuria, hematuria, and a rise in the serum creatinine level are typically seen. The pathogenetic mechanisms of NE kidney failure are incompletely understood. Therefore we studied the infiltrating cell populations and local expression of cytokines and growth factors in the kidney during the acute disease. Results of the histological and immunohistological studies of eight kidney biopsies show mild to moderate interstitial infiltration of lymphocytes, plasma cells, monocytes/macrophages, and polymorphonuclear leukocytes, mainly eosinophilic granulocytes and neutrophils. An increased expression of the cytokines tumor necrosis factor-alpha, transforming growth factor-beta, and platelet-derived growth factor was seen at the same sites mainly in the peritubular area of the distal nephron. Concomitantly also at the same locations expression of the endothelial adhesion molecules ICAM-1, VCAM, and PECAM was seen. Light microscopic changes in tubuli were common. Interestingly, despite the often massive transient proteinuria, no marked changes were seen in the glomeruli of NE kidneys. No evidence of Puumala virus was found in the kidney biopsies.