Immunoglobulin kappa and lambda light chain dual genotype rearrangement in a patient with kappa-secreting B-CLL

The cytogenetics, immunophenotype and immunoglobulin gene rearrangements were analysed in a consecutive series of 56 patients with lymphoma or lymphatic leukaemia. One patient with B-CLL showed monoclonal rearrangements of the constant mu, kappa and lambda genes. The immunophenotype was kappa-secreting indicating expression of one immunoglobulin light kappa allele. Clones of kappa producing B-cells usually show germline lambda genes. The present case may thus be interpreted as a failure of the mechanisms controlling isotypic exclusion at the gene level. Further studies are needed to determine the frequency of such events and whether the patients show distinct clinical or other features.