Neoplastic x and λ cells in a B‐PLL with chromosome translocations of both light chain gene regions

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Abstract
We describe a chromosome translocation t(2;13) (p11‐12;p11) involving the kappa (x) light chain gene region (2p11‐12), and a subsequent translocation t(11;22) (q23;11) involving the lambda (λ) light chain gene region (22qll) within the same clone, in a patient with B‐cell prolym‐phocytic leukaemia (B‐PLL), of whose peripheral mono‐nuclear cells 82% expressed (x) chains and 8% expressed (λ) chains. Electron microscope (EM) studies using the immunogold method showed that both x− and λ‐producing cells were prolymphocytes. Immunoglobulin (Ig) gene analysis by Southern blotting demonstrated rearrangement of both Ig heavy (H) chain genes and one x gene. Although a λ gene rearrangement corresponding to the minor λ‐positive population was not detected, a small monoclonal (M) band of IgM‐λ was present in the serum. The chromosome translocations and the pattern of light chain expression, particularly the λ‐producing cells, are discussed in the light of the restricted light chain expression observed in Burkitt's lymphomas with variant translocations involving the light chain genes.
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