Evidence that multiple myeloma Ig heavy chain VDJ genes contain somatic mutations but show no intraclonal variation.
To investigate whether somatic hypermutation occurs in multiple myeloma (MM) Ig VH region genes, we have cloned and sequenced the expressed VH genes from five cases of MM. The sequences were obtained after polymerase chain reaction (PCR) on total RNA isolated from the bone marrow, using 5' VH family-specific leader and 3' C gamma- or C alpha-specific primers. MM-specific CDR3 oligonucleotides were produced to isolate VH genes expressed by the malignant plasma cells. In all five cases, the productive Ig gene used the VH3 family. Extensive sequence analysis of multiple independent M13 clones showed no intraclonal variation with no evidence for ongoing somatic hypermutation in MM VH region genes. We were able to identify possible germline counterparts of the expressed VH genes in two cases. Comparison of these genes shows that the MM VH region genes have somatic mutations characteristic for an antigen-driven process. In the other three cases, no close homology could be found with published VH3 sequences. These findings implicate that, in MM, clonal proliferation takes place in a cell type that has already passed through the phase of somatic hypermutation.
Bakkus
M H
MH
Department of Hematology-Immunology, Medical School, Vrije Universiteit Brussel, Belgium.
Heirman
C
C
Van Riet
I
I
Van Camp
B
B
Thielemans
K
K
D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D001853:Bone Marrow / Q000473:pathology; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D005803:Genes, Immunoglobulin; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007133:Immunoglobulin Joining Region / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D005810:Multigene Family; D009101:Multiple Myeloma / Q000235:genetics* / Q000276:immunology* / Q000473:pathology; D009154:Mutation; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D004273:DNA, Neoplasm; D007143:Immunoglobulin Heavy Chains; D007133:Immunoglobulin Joining Region; D007135:Immunoglobulin Variable Region; D009838:Oligodeoxyribonucleotides; D012334:RNA, Neoplasm