Lambda-light-chain-mediated anti-GBM disease.

A 77-year-old man presented with macroscopic haematuria and oligo-anuric renal failure. A renal biopsy showed moderate linear glomerular basement membrane (GBM) staining with lambda light chains alone, but both circulating IgG and lambda light chain activity were present. There was no evidence of a serum or urinary paraprotein and a bone marrow biopsy was normal. Serum lambda light chains did not bind to renal GBM when examined by indirect immunofluorescence. This case suggests that light chains are capable of binding directly to epitopes in the GBM and may initiate injury although by a different mechanism from the IgG anti-GBM molecule.