COMPLETE PRIMARY SEQUENCES OF 2 LAMBDA-IMMUNOGLOBULIN LIGHT-CHAINS INMYELOMAS WITH NONAMYLOID (RANDALL-TYPE) LIGHT-CHAIN DEPOSITION DISEASE

We herein report on the first two primary sequences (BOU and RAG) of m onoclonal light chains of the lambda type responsible for nonamyloid l ambda Light chain deposition disease. Both patients were affected with severe forms of myeloma complicated with renal failure. The pathologi cal presentation typically featured Congo red-negative deposits along tubular basement membranes but differed somewhat from the typical ''Ra ndall-type'' kappa Light chain deposition disease: they lacked the pro minent glomerulosclerosis pattern often featuring nonamyloid kappa dep osits and were associated with cylinders or myeloma casts. Both protei n sequences were deduced from those of the corresponding complementary DNAs in the bone marrow plasma cells. For each chain, products of thr ee independent amplifications by polymerase chain reaction were sequen ced and found to be identical. BOU and RAC lambda mRNAs had a normal o verall structure consisting of V lambda 2 segments rearranged to J lam bda 2C lambda 2 but displayed a number of unusual features within thei r primary sequences. These substitutions are likely responsible for ch anges in light chain conformation that promote their aggregation and d eposition along renal tubule basement membranes.