Immunological classification of 31 multiple myeloma patients.

Thirty-one multiple myeloma patients were classified chiefly by heavy and light chain detection of myeloma protein (M protein). The results were as follows: 19 out of the 31 cases belonged to the IgG class, including the following subclasses--IgG1-lambda, 7; IgG1-k, 5; IgG3-lambda, 1; IgG3-k, 2; double M myeloma, 2 (IgG3-lambda + IgG2-k, IgG1-lambda + IgG4-lambda); IgG-lambda, 1; and IgG1-k 1. Seven cases were light chain diseases, of which 4 belonged to lambda type, 2 were k, and one was a double light chain disease. Five cases belonged to the IgA class (IgA-lambda, 3; IgA-k, 2). We found no correlation between electrophoretic mobility and the antigenicity of M protein even within subclasses, and the highly concentrated BJP in urine had a tendency to form light chain polymers, possibly along different polymerization pathways.