Immunofluorescent localization of fibronectin in the human kidney.

Fibronectin is a glycoprotein shown previously to be present on the surfaces of cells, connective tissue matrices, and in extracellular fluids. Its distribution in the human kidney was evaluated by immunofluorescence methods studying 65 renal biopsies with a variety of pathologic disorders. Fibronectin was found in the mesangium of the normal kidney and increased proportionately in the disease states characterized by mesangial expansion. It was visualized in glomerular capillary loops in some biopsies with membranoproliferative glomerulonephritis, diffuse proliferative glomerulonephritis, and membranous nephropathy. Additionally, fibronectin was detected in glomerular crescents, diabetic nodules, vascular thrombi, glomerular sclerosis, and variably in the interstitium.