DISTINCTIVE FEATURES OF IMMUNOGLOBULIN HEAVY-CHAIN VARIABLE REGION GENE REARRANGEMENT IN MULTIPLE-MYELOMA

We have analysed the rearranged Ig heavy chain (IgH) genes in a series of 28 cases of multiple myeloma (MM), in order to extend the study of Ig heavy chain variable (V-H) gene usage in B lymphoid malignancies and to explore the ontogenic compartment from which transformed precursor cells arise in this disease. We were able to amplify 28 rearranged alleles by polymerase chain reaction from 23 of these cases, using a common joining region (J(H)) amplimer together with a panel of V-H family-specific amplimers. The pattern of V-H family usage was similar to that reported in normal peripheral blood B cells with infrequent usage of V(H)5 and V(H)6 genes. However, nucleotide sequence analysis of 17 IgH alleles revealed rearrangement of other V-H family members, closely related to known developmentally regulated V-H genes, some of which are known to be associated with autoimmune specificities. In contrast to previous findings on more immature B lineage malignancies, the rearranged genes diverged extensively from consensus germline sequences, consistent with somatic mutation. These findings support the hypothesis that the major proliferating precursor in MM arises at, or following a stage of T cell-dependent germinal centre proliferation in lymphoid follicles.