Spontaneous immunoglobulin changes in human plasma-cell dyscrasia.

A series of spontaneous changes affecting the nature of the immunoglobulin secretion of plasma cels is described in a patient initially diagnosed as IgG lambda benign monoclonal gammopathy. After several years a slight increase in the amount of serum monoclonal immunoglobulin occurred; shortly thereafter an aggressive form of multiple myeloma was diagnosed. Unexpectedly a rapid spontaneous decrease of the monoclonal immunoglobulin, accompanied by the appearance in the serum of increasing quantities of a complex containing intact lambda light chains, then occurred. Concomitantly a fragment of the corresponding free light chain was was detected in the urine. A parallel is drawn between the facts observed in this patient and in an animal model recently proposed to explain the different types of structural immunoglobulin abnormalities in multiple myeloma.