[Unusual rearrangements of immunoglobulin genes in a patient with IgD/lambda plasmacytoma].

The mechanisms of Ig gene expression in B-lymphocytes are not yet fully understood. A hierarchy of Ig gene rearrangements has been suggested starting with Ig heavy chain genes followed by kappa and lambda light chain genes. According to this principle, B-cells with productive lambda light chain expression have their kappa genes either unproductively rearranged or deleted. By examining B-cells from patients with various lymphoproliferative diseases the developmental hierarchy of the Ig gene rearrangements could be confirmed with one notable exception: in a patient with IgD/lambda-plasmocytoma we found the kappa genes in germ line configuration. This finding points to an aberrant light chain gene expression in IgD-producing plasma cells.