Passage of human Bence Jones protein into the intestinal lumen; an isotopic and immunochemical study in the rat

Abstract

The intestine as a possible site of catabolism of Bence Jones protein has been investigated experimentally in the rat. A pure K-type Bence Jones protein was isolated from the urine of a patient with multiple myeloma, and labelled with 131I in two different protein concentrations. Ten male Wistar rats, divided into two groups, were injected intravenously with the 131I-labelled Bence Jones protein. An intestinal loop, 5 cm long, was isolated surgically between two ligatures and a continuous flow of saline was established by inserting a polyvinyl tube at each of the two extremities of the loop. The intestinal washing fluid was collected at 5-min intervals from the time of the protein injection until 120 min thereafter. Immunoelectrophoresis, Ouchterlony double diffusion test, autoradiography and determination of the protein-bound radioactivity were performed with the intestinal washing fractions and the rat serum. It was found that an appreciable amount of the intravenously administered human Bence Jones protein was cleared through the intestinal wall, and that the clearance values were apparently independent of the two different protein concentrations used. The limitations connected with the experimental conditions and with the arbitrary extension of the findings to the whole length of the small intestine are briefly discussed. In spite of these limitations, the results suggest that the intestine plays an important role for Bence Jones protein catabolism.