Molecular analysis of clonality in plasma cell dyscrasias

It has been suggested that multiple myeloma, generally considered a neoplastic disorder of mature plasma cells, may arise from a pluripotent haemopoietic stem cell. The possibility that circulating lymphocytes derive from the same neoplastic progenitor has been tested in a large number of studies in the past few years, as proof of the interest that this subject is raising among scientists, and also of its elusiveness. We studied a group of 29 patients with plasma cell dyscrasias in order to evaluate clonality of haemopoietic cell populations. The X-linked markers hypoxantine phosphoribosyltransferase (HPRT) and phosphoglycerate kinase (PGK) disclosed no monoclonal component in seven heterozygous women. Analysis of immunoglobulin gene rearrangement with four probes showed a germline configuration in samples from 25/29 patients. Only four bone marrow samples from subjects with aggressive disease had rearranged C mu sequence; one had rearrangement of JH and C mu.