Hodgkin and Reed-Sternberg cells represent an expansion of a single clone originating from a germinal center B-cell with functional immunoglobulin gene rearrangements but defective immunoglobulin transcription

Abstract

Single cell studies aimed at clarifying the nature and clonality of Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin's disease (HD) have so far produced conflicting results. Using an improved single cell procedure, the HRS cells of 25 patients with nodular sclerosing HD lacking B- and T-cell antigens, with and without Epstein-Barr virus infection, were analyzed for the presence of immunoglobulin (Ig) gene rearrangements. One patient with HD developed follicular lymphoma 2 years later. Both lymphomas originated from a common precursor identified as a germinal center B cell. The data show that all but one of the investigated cases harbored rearranged Ig genes, which were clonal in all instances and carried a high load of somatic mutations. The Ig coding capacity was preserved in 18 of the 24 cases (75%) with rearrangements. However, expression of Ig messenger RNA was not detectable in the HRS cells with the exception of Ig kappa light chain expression in some tumor cells of 1 case. The lack of Ig gene transcription in HRS cells was confirmed by analyzing the HD cell lines L428 and KM-H2 in transient transfection experiments. An Ig promoter/enhancer reporter construct showed virtually no activity in these cells compared to 5 control B-cell lines. We conclude that (1) classical HD is a B-cell lymphoma in most instances, (2) HRS cells are clonal without any exception, (3) they are derived from germinal center B-cells that (4) mostly lack crippling mutations but (5) have consistently lost their Ig gene transcription ability, due to functional defects in the Ig gene regulatory elements.

Somatic Hypermutation and B Cell Receptor Selection in Normal and Transformed Human B Cells

“…[7][8][9][10][11] Although HRS cells usually lack expression of typical B cell surface markers, their origin from mature B cells is evident from the finding that they carry rearranged Ig heavy-and light-chain genes. [7][8][9] Moreover, the presence of somatic mutations in the rearranged V genes in nearly all cases established that these cells participated in a GC reaction. Surprisingly, obviously crip-pling mutations (that is, nonsense mutations and deletions causing loss of the correct reading frame) that rendered originally functional V gene rearrangements nonfunctional were identified in a quarter of the cases.…”

“…Surprisingly, obviously crip-pling mutations (that is, nonsense mutations and deletions causing loss of the correct reading frame) that rendered originally functional V gene rearrangements nonfunctional were identified in a quarter of the cases. [7][8][9]12 As GC B cells that acquire such mutations are normally eliminated within the GC, it is likely that the HRS cells in these cases derived from pre-apoptotic GC B cells that were rescued from apoptosis by some transforming event. 12,13 Moreover, as most disadvantagous somatic mutations cannot be easily identified (for example, replacement mutations that reduce the affinity to the antigen), we speculated that HRS cells as a rule derive from crippled GC B cells.…”

“…14 Moreover, HRS cells in classic HL lack expression of Ig (note that most crippling mutations, for example, unfavorable replacement mutations, do not intrinsically cause a down-regulation of Ig transcription). 9 To study the down-regulation of B cell lineage markers in HRS cells systematically, we recently performed gene expression profiling studies with HL cell lines. In a SAGE (serial analysis of gene expression) analysis, the gene expression profile of the HRS cell line L1236 was compared with a profile from human GC B cells.…”

Pathogenesis of Hodgkin's lymphoma

“…The presence of the mutations exclusively in the DLBCL suggests a late transforming event, which happened most likely in the GC because of the occurrence of shared For each of the lymphomas, the breakpoint in the HRS cells and B-NHL cells was identical. 3 NHLs were first diagnosed 3-15 yr before diagnosis of the composite lymphomas. 4 Indication of two copies of the same clonal rearrangement with distinct mutation patterns was obtained in the previous single cell analysis ( and distinct somatic V gene mutations in HRS as well as DLBCL cells.…”

Non‐mediastinal grey zone lymphomas and report from the workshop

“…50% of the ALCL expresses the anaplastic lymphoma kinase (ALK) due to a juxtaposition of the ALK gene on chromosome 2 to another gene, most frequently to the nucleophosmin (NPM) gene on chromosome 5 and (ii) that the ALK fusion gene is consistently absent from the tumor cells of classical HL (6). The grey zone between classical HL and ALK-negative ALCL also seemed to disappear when the tumor cells of classical HL were found by molecular genetic single cell studies to be of B cell origin in 98-99% of the cases (7).…”