Polyacrylamide Gel Electrophoretic and Immunochemical Studies on Urinary Proteins in Sjögren's Syndrome, with Special Reference to Tubular Proteinuria

Abstract

Polyacrylamide gel electrophoretic and immunochemical studies were carried out on urine proteins in Sjögren's syndrome with definite renal tubular dysfunction. Proteinuria showed a distinctive tubular pattern, namely, a small albumin fraction less than 20%, of total urinary proteins, two or three distinct bands in α-region, and post γ-protein. Proteinuria disappeared completely, when metabolic acidosis and hypokalemia were controlled by the administration of alkaline agents, and reappeared in parallel with recurrent metabolic acidosis and hypokalemia after the cessation of treatment, while renal tubular dysfunction persisted during treatment. The effect of metabolic acidosis and/or hypokalemia on defective renal tubular reabsorption of proteins is discussed. The values of relatve 1gG clearance were significantly increased in Sjögren's syndrome compared with those in chronic glomerulonephritis. It seems to suggest increased urinary excretion of low molecular weight protein antigenically related closely to serum lgG, and also to give another evidence of tubular proteinuria in Sjögren's syndrome. © 1970, Tohoku University Medical Press. All rights reserved.