Analysis of monoclonal immunoglobulin light chains in urine using two-dimensional electrophoresis.

High-resolution two-dimensional electrophoresis was used to analyze kappa-type monoclonal immunoglobulin light chains in urine of two patients with multiple myeloma. The patients were treated, remission lasted about 2.5 years. In the period of relapse of the disease, acid isoforms of kappa chains, pI < 4,95, which had not been present in the urine of these patients before, were found in urine of both patients. Kappa-type Bence-Jones protein in urine of one patient showed unusual behavior: It failed to precipitate in the range of 40-60 degrees C or on boiling.