V-domain deposition of lambda Bence Jones protein in the renal tubular epithelial cells in a patient with the adult Fanconi syndrome with myeloma.

An extracted Bence Jones lambda protein from a Japanese patient with myeloma-associated Fanconi syndrome was found to contain 5 components, including the dimer and the monomer of the entire light-chain, the dimer and the monomer of the constant domain, and monomer of the variable domain. The entire amino acid sequence of this lambda chain was completed. The protein, containing 5 components, was injected intraperitoneally in C3H mice, 20 mg for 13 days and 200 mg for 3 days. Both groups of C3H mice showed a renal proximal tubular deposition of variable domain fragment of the Bence Jones protein by immunoperoxidase staining. Other control Bence Jones proteins of the lambda type and serum albumin were negative in terms of deposition in the epithelial tubular cells. It is also shown that the proximal tubules of the biopsied kidney from the patient had a deposition of variable domain fragment of Bence Jones protein. Thus, the myeloma-associated Fanconi syndrome could be included in the spectrum of light-chain associated disease or monoclonal Ig deposition disease. This is the first case of lambda type Bence Jones protein with a complete amino acid sequence analysis found in Fanconi syndrome with myeloma, demonstrating the deposition of the variable domain in the proximal tubules of the kidney.