Selective induction of light chain synthesis in cultures of blood lymphocytes from patients with IgG myelomatosis.

In the present study evidence is provided that neoplastic B cells from the blood from four of 24 patients with myelomatosis were activated selectively with polyclonal B cell mitogens. In three of these patients the activated cells produced light chains without heavy chains; of these, two patients had IgGK paraproteins and one had free lambda light chain disease. The ratio of kappa-expressing to lambda-expressing B cells in the initial blood B cell preparations was within the range for healthy controls for all four patients where neoplastic B cells were selectively activated. It is concluded that in some patients with myelomatosis the neoplastic clone is a mosaic of: (1) cells capable of synthesizing both light and heavy chains with (2) cells producing light chains only.