The renal and hepatic distribution of Bence Jones proteins depends on glycosylation: a scintigraphic study in rats

Abstract The aim of the present study was to evaluate renal and liver distribu-tion of two monoclonal immunoglobulin light chains. The chains werepurified individually from the urine of patients with multiple myelomaand characterized as lambda light chains with a molecular mass of 28kDa. They were named BJg (high amount of galactose residuesexposed) and BJs (sialic acid residues exposed) on the basis ofcarbohydrate content. A scintigraphic study was performed on maleWistar rats weighing 250 g for 60 min after iv administration of 1 mgof each protein (7.4 MBq), as the intact proteins and also aftercarbohydrate oxidation. Images were obtained with a Siemens gammacamera with a high-resolution collimator and processed with aMicroDelta system. Hepatic and renal distribution were establishedand are reported as percent of injected dose. Liver uptake of BJg wassignificantly higher than liver uptake of BJs (94.3 vs 81.4%) (P<0.05).This contributed to its greater removal from the intravascular compart-ment, and consequently lower kidney accumulation of BJg in com-parison to BJs (5.7 vs 18.6%) (P<0.05). After carbohydrate oxidation,there was a decrease in hepatic accumulation of both proteins andconsequently a higher renal overload. The tissue distribution ofperiodate-treated BJg was similar to that of native BJs: 82.7 vs 81.4%in the liver and 17.3 vs 18.6% in the kidneys. These observationsindicate the important role of sugar residues of Bence Jones proteinsfor their recognition by specific membrane receptors, which leads todifferential tissue accumulation and possible toxicity.