IMMUNOHISTOCHEMICAL AND LECTIN DISSECTION OF THE HUMAN NEPHRON IN HEALTH AND DISEASE

Many renal diseases involving the tubular epithelium appear to perfere ntially affect certain nephron segments. While major portions of the n ephron, such as proximal and distal convoluted tubules and collecting ducts, can be identified in the normal kidney, the distinction of dise ased nephron segments can be difficult in tissue sections. Thus, to id entify which nephron segments are involved in pathologic changes is us ually impossible by routine histologic examination alone. Recently ant ibody and lectin probes that react with specific nephron segment-speci fic epitopes and carbohydrates, respectively, have become available. S ome of these antibodies and lectins can be used on formalin-fixed, par affin-embedded, archival tissues. Because renal tubules appear to reta in their nephron segment-specific epitopes and glycoprotein moieties u nder most pathologic conditions, these nephron segment-specific tubula r epithelial markers provide a method to study renal diseases involvin g the tubular system also in archival material. Such nephron segment-s pecific tubular epithelial markers are: the lectins, Tetragonolobus pu rpureas and Phaseolus vulgaris erythroagglutinin (proximal tubular mar kers); antibodies to low-molecular-weight cytokeratin (AE1/AE3); epith elial membrane antigen and the lectin Arachis hypogaea (distal nephron [distal convoluted tubule and collecting duct] markers); and antibodi es to Tamm-Horsfall protein (labeling the thick ascending limb of Henl e). We review the application of these and other renal tubular epithel ial markers in the normal kidney and in various renal diseases includi ng cystic disease of the kidney, interstitial nephritis, tubular atrop hy, acute tubular necrosis, myeloma cast nephropathy, and renal tumors .