Evidence for a bone marrow B cell transcribing malignant plasma cell VDJ joined to C mu sequence in immunoglobulin (IgG)- and IgA-secreting multiple myelomas.

Abstract

SummaryMultiple myeloma is a B cell malignancy characterized by the expansion of plasma cells producing monodonal immunoglobulins (Ig). It has been regarded as a tumor arising at the B, pre-B lymphocyte, or even stem cell level. Precursor cells are presumed to proliferate and differentiate giving rise to the plasma cell donal expansion. Antigenic features and specific Ig gene rearrangement shared by B lymphocytes and myeloma ceils have supported this hypothesis. However, the existence of such a precursor is based upon indirect evidence and is still an open question. During differentiation, B cells rearrange variable (V) regions of Ig heavy chain genes, providing a specific marker of clonality. Using an anchor polymerase chain reaction assay, these rearranged regions from five patients with multiple myeloma were cloned and sequenced. The switch of the Ig constant (C) region was used to define the B call differentiation stage: V regions are linked to C# genes in pre-B and B lymphocytes (pre-switch B cells), but to C'I/or Cot in post-switch B lymphocytes and plasma ceUs (post-switch B cells). Analysis of bone marrow calls at diagnosis revealed the presence of pre-switch B ceils bearing plasma cell V regions still joined to the C/~ gene. These cells were not identified in peripheral blood, where tumor post-switch B cells were detected. These pre-switch B cells may be regarded as potential myeloma cell precursors.M ultiple myeloma is a B-cell malignancy characterized by a clonal expansion of plasma cells producing monoclonal Ig. Several lines of evidence suggest B lymphocyte involvement in the pathogenesis of multiple myeloma. First, B lymphocytes, or even pre-B lymphocytes expressing the same idiotype as myeloma protein have been found in bone marrow and peripheral blood (1-3). Second, malignant plasma cells expressing pre-B lymphocyte antigens have been described (4-6). Third, PBMC may show the same IgH gene rearrangement as myeloma cells (7,8). However, the existence of a myeloma cell precursor is still a subject of controversy (9, 10).Our molecular approach involved in the use of tumor cell IgH V region as a marker ofclonality. The antigen specificity in B lymphocyte clones is derived primarily from the rearrangement of V, D, and J segments of H chain genes. Assembled variable regions (VDJ) contain three CDR that codify for the antigen-binding site. These regions are unique to each B cell done (11), and can be used to define oligonudeotide primers and probes characteristic of the tumor cell After antigenic stimulation, B lymphocytes switch the IgH isotype by deleting the C# gene, without changing the VDJ-encoded specificity Hence, pre-B and B lymphocytes (pre-switch B cells) can be discriminated from post-switch B lymphocytes and plasma calls (post-switch B cells) because of their C region usage.We reasoned that myeloma cell precursor may be located at the pre-switch B cell stage, and be identifiable as a cell in which the IgH transcript is composed of plasma ceU VDJ still joined to C# gene. The sequence of the p...

Paraproteinemia, plasmacytoma, myeloma and HIV infection

“…39 Thus, transformation occurs after somatic hypermutation, and the lack of subsequent mutation indicates that the malignant, clonal lymphocyte-plasma cell population has escaped the antigen selection process. Lymphocyte populations clonally related to myeloma cells undergo class switching, 30,31,36,41 indicating that transformation occurs prior to class switching and leaves intact either the switching mechanisms or a preprogrammed switch. The transformed population in myeloma thus appears to be restricted to the myelomatous plasma cells and clonally related, hypermutated, pre-switched B lymphocyte populations found in the bone marrow or periphery.…”

Origin and diversification of the clonogenic cell in multiple myeloma: lessons from the immunoglobulin repertoire

“…The application of an allelespecific oligonucleotide (ASO)-based PCR with ASO derived from the sequence of CDR3 analyzed in each case enabled the detection of a B cell population clonally related to the plasma cell tumor. [24][25][26] Using this strategy, it became feasible to demonstrate the existence of pre-switch /␦ isotype bearing B cells clonally identical to ␥ or ␣ isotype-bearing myeloma cells from the BM of the patients. Sorting of BM B cells into CD45 + and CD38 + populations resulted in lineage-specific expression of the clonally related RNA, with the C and C␦ isotypes expressed by the CD45 + and the C␥ or C␣ isotypes by the CD38 + population.…”

“…[24][25][26] The only definite proof that B cells at various stages of development are clonally related derived from the analysis of their Ig rearrangements and, more precisely, the unique sequence of their VDJ junctions, which, in case of clonal relationship, should be identical. The application of an allelespecific oligonucleotide (ASO)-based PCR with ASO derived from the sequence of CDR3 analyzed in each case enabled the detection of a B cell population clonally related to the plasma cell tumor.…”

Long-term follow-up of idiotype vaccination in human myeloma as a maintenance therapy after high-dose chemotherapy

“…In two patients, bone marrow and peripheral blood were evaluated for the presence of residual myeloma cells by PCR, using oligonucleotide primers and probes derived from the tumor-specific Ig heavy-chain gene sequences, as previously reported. 20,21 Progression-free survival (PFS) was measured from the date of remission achievement to the date of progression or last followup. Overall survival (OS) was measured from the date of diagnosis to the date of death or last follow-up.…”