Polymeric Bence Jones proteins in serum in myeloma patients with renal insufficiency

The polymeric forms of Bence Jones protein (BJ) in serum and the influence on renal function were investigated in 59 patients with multiple myeloma and 2 with Waldenström's macroglobulinemia. Eight of 35 patients with kappa and 26 with lambda type BJ protein had decreased renal function. The investigation showed a considerable variation between patients in serum concentrations of tetrameric (T), dimeric (D) and monomeric (M) forms of BJ protein. A significantly higher fraction of D forms of BJ protein resulting in a high D/M ratio was found in the myeloma patients compared with polyclonal light chains in 10 normal controls. The renal function in multiple myeloma was, however, not correlated to the D/M ratio or to the BJ protein tetramers. This suggests that the nephrotoxicity of BJ proteins is not associated with polymerization of BJ proteins in serum. BJ proteins of aberrant size were found in 3 patients with rapidly decreasing renal function. Histological investigation in 2 of these patients revealed nodular glomerulosclerosis.