Clinical significance of a multiple myeloma cell line, derived from a case associated with hyperammonemia

Recently, there have been several reports describing patients with multiple myeloma complicated by consciousness disturbance due to hyperammonemia. Here we report a patient with multiple myeloma and hyperammonemia, who died after rapid progression of the disease. A 71-year-old man who had been diagnosed as having Bence Jones protein (kappa)-type multiple myeloma in 1996 was readmitted to our hospital in February 1997 because of worsening bone pain, renal dysfunction, and hypercalcemia. Bone marrow aspiration yielded an almost dry tap, and the bone marrow was found to be completely occupied by immature plasma cells. Although liver dysfunction was slight, the serum ammonia level was high and increased gradually. Despite treatment, the patient died due to cerebral embolism and progression of plasmacytic leukemia in October 1997. Peripheral blood sampled at the time of death showed a serum ammonia level of 204 micrograms/dl, and the myeloma calls were cultured using monolayered bone marrow stromal cells as feeder cells. This led to the successful establishment of a cell line. The level of ammonia in the supernatant was high, indicating that the cultured myeloma cells produced and released ammonia.