Prevalence of monoclonal Ig with lambda light chains in chronic myelocytic leukaemia.

Light chains from seven of eight monoclonal Ig detected in the serum of patients with chronic myelocytic leukaemia (CML) were of the lambda isotype. Although the presence of monoclonal Ig in CML is distinctly unusual, this prevalence of lambda chains is unlikely to be a mere coincidence. All patients had otherwise typical clinical, chromosomal and molecular (bcr rearrangements) features of classical CML. The lambda locus appeared unaltered. Only two patients had an excess of dystrophic plasma cells suggestive of multiple myeloma.