Immunoglobulin Lambda Light Chain Genes Research Articles

Contribution of immunoglobulin lambda light chain gene rearrangement analysis in the diagnosis of B‐cell neoplasms

Identification of clonal IGH, IGK and IGL gene rearrangements offers diagnostic adjunct in suspected B-cell neoplasms. However, many centres omit IGL analysis as its value is uncertain. A review of 567 cases with IGH, IGK and IGL rearrangement assessed using BIOMED-2 assays showed clonal immunoglobulin gene rearrangement in 54% of cases, of which 24% had a clonal IGL rearrangement. In two cases, the clonal rearrangement was detected exclusively by IGL analysis. This finding demonstrates the added value of IGL analysis for clonality assessment, especially in suspected B-cell neoplasms in which a clonal IGH and/or IGK rearrangement is not detected or is equivocal.

Diversity of immunoglobulin lambda light chain gene usage over developmental stages in the horse

To further studies of neonatal immune responses to pathogens and vaccination, we investigated the dynamics of B lymphocyte development and immunoglobulin (Ig) gene diversity. Previously we demonstrated that equine fetal Ig VDJ sequences exhibit combinatorial and junctional diversity levels comparable to those of adult Ig VDJ sequences. Herein, RACE clones from fetal, neonatal, foal, and adult lymphoid tissue were assessed for Ig lambda light chain combinatorial, junctional, and sequence diversity. Remarkably, more lambda variable genes (IGLV) were used during fetal life than later stages and IGLV gene usage differed significantly with time, in contrast to the Ig heavy chain. Junctional diversity measured by CDR3L length was constant over time. Comparison of Ig lambda transcripts to germline revealed significant increases in nucleotide diversity over time, even during fetal life. These results suggest that the Ig lambda light chain provides an additional dimension of diversity to the equine Ig repertoire.

Translocation (18;22)(q21;q11) in B-cell lymphomas: a report of 4 cases and review of the literature

Follicular lymphomas characteristically carry t(14;18)(q32;q21) which results in IGH-BCL-2 fusion. Variant translocations that juxtapose the BCL-2 gene with the immunoglobulin kappa (2p11) and lambda (22q11) light chain genes are rare. We report 4 cases of B-cell lymphoma/leukemia associated with t(18;22)(q21;q11). The t(18;22)(q21;q11) was the sole aberration identified by conventional cytogenetics in 2 cases. Three cases were classified as chronic lymphocytic leukemia, and one as follicular lymphoma based on morphology and immunophenotype. Fluorescence in situ hybridization analysis was performed on all 4 cases using a BCL-2 breakapart probe. The BCL-2 gene was rearranged in all cases. Immunoglobulin lambda light chain gene rearrangement was shown in 3 cases using bacterial artificial chromosome probes spanning the variable and constant clusters of the IGlambda gene. Each case was negative for MALT-1 rearrangement using a MALT-1 breakapart probe. These cases illustrate that t(18;22)(q21;q11) is more commonly observed in chronic lymphocytic leukemia and may represent either an initial or secondary genetic event.

Early Vlambda diversification in sheep.

This study examined a number of tissues during early gestation in foetal sheep to determine the earliest site of Vlambda expression and time of generation of the Vlambda repertoire. Tissues, including spleen, liver, gut, blood and bone marrow, were obtained from 48, 55, 60 and 63 gestational day (g.d.) ovine foetuses and cDNA libraries were prepared from them by reverse transcription-polymerase chain reaction. Clones were randomly selected from cDNA libraries and subjected to sequencing. Analysis of these sequences and comparison with a pool of germline genes led to the following conclusions. The expression of Vlambda occurs earlier in spleen (48 g.d.) than in all of the other tissues examined. Also, diversity is seen earlier and at higher levels in early foetal spleen than in all of the other tissues examined. In this regard, it is notable that splenic Vlambda expression is readily apparent even before such gut-associated lymphoid tissue as the ileal Peyer's patch (IPP) has developed. Two germline Vlambda genes, 5.1 and 5.3 predominate in early immunoglobulin lambda light-chain gene rearrangement. Examination of Jlambda usage revealed the existence of a new Jlambda gene and its utilization during the early phases of the development of the ovine antibody repertoire. This study indicates that sites other than the IPP contribute to the diversification of the Vlambda repertoire in sheep. We suggest that it is likely that foetal spleen may provide a partially diversified B-cell repertoire before the IPP becomes active as a major site for massive clonal expansion and extensive diversification of B cells.

Diffuse Large Cell, B-cell Type Lymphoma with a Novel Translocation (2;22)(p23;q11.2)

We observed a translocation (2;22)(p23;q11.2) in the bone marrow cells of a patient with multiple subcutaneous nodules. Tumor histology and immunohistochemical staining demonstrated a malignant lymphoma, diffuse large cell type, displaying a CD30 negative B cell immunophenotype. To our knowledge, this is the first report of this specific translocation in lymphoma, which may join the site of the anaplastic lymphoma kinase (ALK) gene at 2p23 to the region of the immunoglobulin lambda light chain gene at 22q11.2. The ALK gene was initially identified through its involvement in the t(2;5)(p23;q35) found most commonly in anaplastic large cell lymphoma. This observation in a CD30 negative large cell lymphoma of B cell lineage further extends the relationship of anaplastic large cell morphology, ALK activation, lymphoid lineage, and expression of the CD30 antigen.

The chicken immunoglobulin lambda light chain gene is transcriptionally controlled by a modularly organized enhancer and an octamer-dependent silencer.

Characterization of the regulatory elements involved in V(D)J recombination is crucial for understanding development of the B and T cell immune repertoire. Previously we have shown that the chicken immunoglobulin lambda light chain gene (CLLCG) undergoes lymphoid-specific rearrangement in transgenic mice. The whole gene is only 10 kb in length and contains all phylogenetically conserved target sites for recombinational and transcriptional regulation. In this study we have localized an enhancer element in a region 4 kb downstream of the constant (C) region. The 467 bp element can be subdivided into three subfragments. The previously detected silencer element on the V-J intervening sequence is shown to be localized on a 500 bp fragment. Partial silencer activity is retained on a 250 bp fragment, which includes an octamer motif. By mutational analysis this octamer is shown to be essential for B cell- but not for T cell-specific silencer function. The silencer represses transcription directed by heterologous elements like the SV 40 promoter or the Ig kappa 3' enhancer. We propose that transcription of the unrearranged and rearranged Ig genes is regulated by complex interactions between different modules from the promoter, enhancer and silencer, which is eliminated by recombination during B cell development.

Analysis of individual immunoglobulin lambda light chain genes amplified from single cells is inconsistent with variable region gene conversion in germinal-center B cell somatic mutation.

Responding B cells in specific immune responses diversify their immunoglobulin genes and are selected on their variant antigen receptors in the microenvironment of the germinal center. The patterns of mutations previously reported for immunglobulin (Ig) genes have supported mechanistic hypotheses of either error-prone DNA synthesis or templated variable region gene conversion as the underlying mechanism in the generation of these mutations. To assess the role of gene conversion in germinal-center somatic mutation, we chose to examine nucleotide changes in mouse lambda light chain genes which arose in response to a specific antigen. Laboratory mice possess three V lambda subexons, two of which differ from one another by only seven nucleotides, making these two subexons ideal for gene conversion. In the current study, we used six-parameter flow cytometry to isolate single lambda light chain-expressing germinal-center B cells from two different time points in a primary immune response. We then individually amplified and sequenced individual V lambda 1 genes from these single cells for mutational analysis. None of the 32 V lambda 1 genes, containing a total of 40 mutations, showed evidence of gene conversion from either of the other V lambda subexons. Features such as the replacement to silent ratio of the mutations documented at the earlier time point indicate an absence of antigen-driven selection. These data indicate that V region gene conversion does not contribute to germinal-center somatic mutation and that gene conversion is not responsible for targeting mutation specifically to rearranged Ig genes. The biological implications are discussed.

Immunoglobulin lambda light-chain-related genes 14.1 and 16.1 are expressed in pre-B cells and may encode the human immunoglobulin omega light-chain protein.

Human pre-B cells, which produce immunoglobulin heavy chain but do not produce immunoglobulin light chain, are shown to contain a 1-kilobase transcript homologous to immunoglobulin lambda light-chain genes. Detailed analysis of RNA and cDNA clones derived from these transcripts reveals that they originate from the distinct immunoglobulin lambda-like genes 14.1/16.1. Sequence analysis of these clones reveals a long open reading frame, beginning with an ATG, capable of encoding a protein of 214 amino acids with an unprocessed molecular weight of 22,944. The C-terminal half of this predicted protein is highly homologous to immunoglobulin lambda light-chain joining and constant region protein sequence, while the amino-terminal end does not share homology with variable regions. Unlike immunoglobulin genes, these genes do not undergo rearrangement prior to expression. Analysis of a panel of 26 hematopoietic cell lines reveals that expression of 14.1/16.1 is limited to pre-B cells and one B-cell line, which, like the pre-B cells, is surface immunoglobulin negative. Antisera raised against a peptide whose sequence was predicted from the 14.1 cDNA sequence identifies a 22-kDa protein in human pre-B cells. Immunoprecipitation of immunoglobulin mu-chain from these pre-B cells with anti-immunoglobulin mu antibody coprecipitates a 22-kDa protein, which is a candidate for the human immunoglobulin omega light-chain protein and may be the protein product of the 14.1/16.1 genes.

Two pseudogenes among three rat immunoglobulin lambda chain genes

In order to examine the number and organization of the immunoglobulin lambda light chain genes of the rat, we have used mouse lambda chain cDNA probes to isolate hybridizing fragments from a partial Eco RI rat liver DNA library. We have determined the partial nucleotide sequence of two such clones. One clone, containing a 5.8 kb EcoRI insert which hybridizes to both mouse Cλ1 and Cλ2 probes, includes an apparently expressible Cλ2-like gene as well as a CλI-like pseudogene (ψCλ1.1), arranged similarly to the mouse Cλ gene complexes. Sequence analysis of a second cloned EcoRI fragment (1.15 kb in length) revealed part of a second CλI-like pseudogene (ψCλ1.2), the coding regions of both pseudogenes being interrupted by multiple frame-shifting size differences. In the case of υCλ 1.2, the degree of sequence identity with mouse Cλ 1 drops abruptly immediately following the termination codon, suggesting that translocation events have played a role in its generation. These two rat pseudogenes, and the mouse Cλ4 pseudogene, clearly have been rendered unexpressible by separate evolutionary events. Comparisons between Cλ coding and non-coding regions of rats and mice indicate that some of the unusual patterns of divergence we have observed in recently diverged C k genes may exist in Cλ genes as well.

Variable amplification of immunoglobulin lambda light-chain genes in human populations.

The human lambda immunoglobulin locus displays a series of restriction fragment length polymorphisms that are readily detected in small populations of normal individuals. Similar polymorphisms appear in populations of wild mice, suggesting that the lambda locus is subject to rapid variation within a single species. Here we show that the polymorphisms seen in the human lambda locus seem to have arisen from unequal meiotic crossing over, altering the number of lambda from as few as six to as many as nine per haploid genome. This expansion and contraction in the number of human lambda genes is significant in that it may affect an individual's capacity to produce variation among lambda light chain genes.

DNA sequences of the joining regions of mouse lambda light chain immunoglobulin genes.

The joining (J) segments of mouse immunoglobulin lambda light chain genes, lambda 2, lambda 3, and a presumptive lambda 4, were cloned, and their sequences were determined and compared with that of lambda 1. Although all the lambda J segments share sequence homology, the J1 and J4 segments and the J2 and J3 segments, respectively, are more homologous. These sequence data, together with the fact that present day lambda genes occur in two clusters, 5' J3C3J1C1 3' and 5' J2C2J4C4 3', further substantiates a probable evolutionary duplication unit, JIICIIJICI, with II the precursor of lambda 3 and lambda 2 and I the precursor of lambda I and lambda 4. From the J4 sequence, we conclude that the lambda 4 gene is most likely nonfunctional (i.e., a pseudogene). The signal nonamer sequence 5' to J3 differs from that of J1 in two consecutive base pairs. This difference could account in part for the lower level of expression of lambda 3 as compared with lambda 1 in mouse serum.