BENCE JONES PROTEINURIA IN BENIGN MONOCLONAL GAMMAPATHIES

Abstract The possibility and the extent to which detection of Bence Jones proteinuria might be used as a clinical differential criterion between benign and malignant monoclonal gammapathies has been investigated. Clinical and laboratory studies were carried out in 42 subjects with an “essential” serum M‐component and, by comparison, in 46 patients with myelomatosis and in ten with macroglobulinemia Waldenström. The heat precipitation test was found weakly positive in only one urine sample from the benign cases (2.3%), as compared with 32.6% of the myeloma cases and 20% of those with macroglobulinemia. However, by combining agarose‐electrophoresis and immunoelectrophoresis of concentrated urine, a urinary light chain component was demonstrated in 23.8% of the benign gammapathies. For myelomatosis and primary macroglobulinemia the corresponding figures were 67.3% and 60%, respectively. The amount of Bence Jones proteinuria never exceeded 60 mg/1 in the benign forms, whereas in the malignant forms it changed considerably from case to case and could reach values of as much as 10 g/1. Wide variations of pH and temperature were studied for their effect upon the thermal behaviour of two kappa‐type Bence Jones proteins, isolated from the urines of two subjects with benign monoclonal gammapathies. Within the limits investigated the physico‐chemical properties of these benign‐type Bence Jones proteins did not differ apparently from those described as characteristic of Bence Jones protein in myelomatosis. The kappa/lambda ratio of the serum M‐components in the “essential” cases did not show any preferential synthesis as compared with myelomatosis and normal immunoglobulins. This indicates that the benign monoclonal mutation of kappa‐ and lambda‐synthesizing cells may develop at a rate proportional to their normal occurrence.